To the Editor of SCIENTIFIC AMERICAN: Probably many readers of the SCIEK' TIFIC AMERICAN have wondered what phenomenon would appear were the sun to be annihilated instantly. Many, I suppose, thought that the light would be shut off immediately. With the following explanation and accompanying diagrams I shall attempt to show -what the result would be. The diameter of the sun is known to be roughly 866,000 miles, and the speed of light to be 186,000 miles per second. Now, while the light of the sun appears to come from a disk, it really comes from a curved surface, the center of which is nearly 433,000 miles nearer us than the edges. Let A, ^, A' be the visi· i ble p ortion of the sun. (The fgure is a cross sectio n.) T hen the light from th e point B has a shorter distance to travel to the surface of the earth by 433,000 miles, or more than 2.3 light seconds. Therefore, the light from B reaches the surface of the earth 2.3+ seconds before the light from A, A'. Now, supposing the light all over the sun should cease instantly. The light from B would stop 2.3+ seconds sooner than the light from A, A'. Therefore, if the sun were suddenly annihilated, if one were observing at the time, about eight minutes (the time light takes to travel from the sun to the earth) after the sun would appear black at the cenier, gradually increasing, until 2.3+ seconds after the sun began to grow black, it would be entirely invisible. Viola, Idaho. K. M. ADAMS. Why do Not Human Eyes Shine at Night? To the Editor of SCIENTIFIC AMERICAN: When hunting at night, one can see the eyes of animals shine pale green or red, when artificial light in directed on them; the same is seen when motoring at night with sheep, cattle, dogs, cats, etc. But this is never seen with human eyes. Why is it? The eyes seem to he made exactly alike. I think the above subject has never before been discussed, in fact, when I speak to anyone about it they say they have not noticed it. WALTER WINANS. Surrenden Park, Pluckley, Kent. [Your question “Why do Not Human Eyes Shine at Night?” i' not difficult to answer. The coat of the eye which carries the blood vessels, otherv'ise known as the choroid coat, is locally differentiated into a structure called the tape-tum. This tapetum, situated on the back portion of the choroid coat, varies widely in different animals, both in· appearance and detail of structure. In the cat the tapetum, formed by a layer of cells containing crystals, Is of a brilliant blue or green color, and it is the reflection and incident iridescence of light falling on this area that causes th e eye to “shine” in the so·called dark. I have kept a eat's eye pre ser ved in No Skidding No Rim-Cutting 10% Oversize Note the Double-Thick Tread Note the Deep-Cut Blocks Note the Countless Edges and Angles Here's Your Ideal Non-Skid Tread Over 700,000 Sold When you go to buy tires, please consider these facts about Goodyear No-Rim-Cut tin,s. The demand for these tires, in the past two years, has increased by 500 per cent. That demand has compelled us to increase our capacity to 3,800 tires daily. Over 700,000 have been sold to date. As a result of their use-on tens of thousands of cars - these tires now outsell any other tires in existence. These are the tires you are bound to buy when you know the facts about them. Millions Saved No-Rim-Cut tires won their amazing prestige by cutting tire bills in two. They have saved motor car owners many millions of dollars. These tires are the final result of 13 years spent in tire making. Men can never make tires any better. Then, our patented features make these tires proof against rim-cutting. With the ordinary tires - with clincher tires - 23 per cen t of all ruined tires are rim-cut. A punctured tire may be wrecked in a single block. . Out of 700,000 of these patented tires, not 0 n e has ever rim-cut. Thatworry and expense is forever avoided. Then, No-Rim -Cu t tires are 10 per cent oversize. That is due to the fact of the hookless base. These tires are not hooked to the rims. That means 10 per cent more air -10 per cent greater carrying capacity. And that, with the average car, adds 25 per cent to the tire mileage. GOODJ^EAR No-Rim-Cut Tires With or Without Non-Skid Treads With these tires you save rim-cutting. You save the blowouts due to overloading. You get extra capacity without extra cost. For these patented tires now cost no more than other standard tires. The result of this is, under average conditions, to cut tire cost one-half. Now Double-Thick Non-Skid Treads Now we have added, for those who want it, a double-thick Non-Skid tread. Not any mere makeshift-not a fimsy, short-lived protection. This is an extra tread, about as thick as our regular, vulcanized onto the regular tread. This extra thickness permits of deep-cut blocks. Those blocks are made of immensely tough rubber. They present to the road surface countless edges and angles. And they don't soon wear down. Danger of puncture is reduced 30 per cent by this double tread. Each block widens out at the base, so the stram is distributed over just as much surface as with a smooth-tread tire. Those are some of the dozen advantages over any other non-skid tread. No-Rim-Cut tires with this N on-Skid tread put an end to rim-cutting, an end to skidding and an end to overloading. And those are the three greatest tire troubles. Our Tire Book, based on 13 years of tire making, is filled with facts you should know. Ask us to mail it to you. The Goodyear Tire&Rubber Co. First Street, - Akron, Ohio Branches and Agencies in 103 Principal Cities We Make All Kinds of>Rubber Tires, Tire Accessories and Repair Outfits Main Canadian Office, Toronto, Onto Canadian Factory, BowmanviIle, Onto 484 SCIENTIFIC AMERICAN November 25, 1 9 1 1 Big profits Litt^for you This is Tom Thumb-one of the famous engines in the I H C line. Tom Thumb develops more than one-horse power. In the shop it will operate a lathe, drill-press, emery grinder or other small machines. It is powerful enough to pump all the water needed on the ordinary farm-will run the cream separator, grindstone, bone cutter, churn, small corn sheller, washing machine, etc. This little work saver is exceptionally simple and strong and will give steady economical power for years. It is an I H C through and through. It is made of the same high grade materials and is built and tested in the thorough manner that distinguishes all I H C Gasoline Engines Tom Thumb comes all complete, including governor, spark plug, batteries, tools, etc. No water tank is needed. The cooling is done by air. Write for more information about I H C engines. They are made in many styles and sizes for every need. 1 to SOhorse power; stationary Of portable; air or water cooled; built to operate aD gas. 23soline. kerosene, distillate or alcohol. Also gasoline and kerosene tractors. 12 to 4S-horSe power. Write now for catalo/ue a:.d any special information you desire. Address: International Harvester Company of America (Incorporated) 15 Harve8ter Bldg Chicago USA A Home Made Alternating Current Motor MUNN&CO. 361 BROADWAY NEW YORK f Inc. Read Supplement 1688 for a good, clear article by F. E. Ward, E. E., on the making of a one.eighth horse power alternating current motor. The motor can be constructed by anyone of ordinary skill in the use of tools who has access to a screw· cutting lathe with a swing of nine inches or more. The motor i. designed to run on the 100 to 120 volt, 6O-cycle, single-phase alternating current circuit, now in wide-spread use for the lighting of dwellings. The motor will drive a J6.inch brass fan, a small lathe, or a 50-watt dynamo flr generating direct current for charging storage batteries, and in fact will do almost any kind of work that can be done by one-man power. Order from your newsdealer or from us. Before Subscribing for your periodicals, you should see our Catalog, containing a· list of 3000 magazines and club offers, Jt prices that will surprise you. Itjs the handsomest and most complete Magazine Guide ever published, filled with all the latest and best club offers at rates, lower than you think possible. YOU c a nnot afford to be wi t ho u t it. In orderin g your magazines, be sure you use a HANSON catalog. Accept no substitute. The name HANSON stands for promptness and reliability in the magazine field. It is so accepted by all leading publishers. THIS CATALOG FOR 1912 is FREE lor the aSkiDq. It will. SAVE YOU MONEY ' .Send us your name and address today. We'll do the rest. M. BNSON MAGAZINE AGENCY 240 HansoD Block, Lexington, Ky. _______FILL IN THIS COUPON AND MAIL 'o US____________ J. 1. HANSON. Lexington. Ky. Please send me FREE of expensf to me, this Catalog for 1912. . NAME................ Street Addres8 or County glycerin jelly for five years, which still shows undiminished iridescence when a ray of light is allowed to fall upon its tapetum. The eye of a horse kept for a like period gives the same result. In man the tapetum is insignificant, and therefore the phenomenon of “shining” at night is not observed. Between the tapetum of man and that of the cat we find all grades of development in the other mammals, and a critical examination will show that the degree of “shining” in the dark will vary according to this development. R. W. TOWER, Curator of Physiology, American Museum of Natural History, New York.] Association of Variable Star Observers To the Editor of SCIENTIFIC AMERICAN: Notice is hereby given that an association of variable star observers has recently been organized in this country. All those interested in astronomy possessing telescopes of three inches aperture or larger are cordially invited to co·operate in this work. This plan has received the indorsement of Prof. E. C. Pickering, director of the Harvard College Observatory, and monthly reports of the work of this association are sent to the Harvard Observatory. Here is an excellent opportunity for observers to render science practical aid, and use their telescopes to good advantage. The work is not diff· cult, involves no mathematics, and requires no experience. Those desiring further information respecting this line of observation work are requested to address WILLIAM TYLER OLCOTT. NOl'wich, Conn. Zeppelin's “Schwaben" (OoncZuded from page 47S) honored aeroplane rudders, fore and aft, were removed-uite a revolutionary step, because they had always proved efficient. Only one set of them was now attached to a more graceful single rudder frame at the extreme rear, where they were combined with vertical rudders and cleverly supported by the stabilizing fins. It was found that thus friction and head resistance was cut down, steadiness improved and the efficiency of all rudders wonderfully increased, for the big ship could now be turned completely within a circle of only 1,600 feet in diameter. It was surprising that the lifting power of the ship suffered nothing from tao removal of its “aeroplanes;” the kUe effect of the smooth cylindrical hull so well replaced theirs that instead of falling below the floating power of the “Deutschland,” that of the “Schwaben” was essentially increased by her greater speed. The ineffdency of an aeroplane which is very long in its line of motion, is improved in a dirigible by the small weight it has to carry dynamically per square foot of its immense surface. Incessant experimenting with propellers is going on in the Zeppelin laboratory, and the “Schwaben's” large four· and two· bladed ones showed increased efficiency. The brackets holding them were cleverly robbed of much head resistance and turned into useful and ornamental steadying f;s by a cloth covering. Structural strength was increased at the essential points. The cars and the cabin were built of corrugated aluminium. The size and strength of the pneumatic buffers under the cars was increased. The success of the “Schwaben's” many passenger trips is not only due to her own greater power, but also to perfected methods of handling rigid dirigibles. There are mechanical docking devices in the new sheds which hold the ship securely until it is safe in the open air, so that it may enter and leave without danger. A rail on each side of the shed runs far out into the open through each of the doors at both ends. Each length of rail is made of two narrow channel plates, rivetted together back to back. Two sets of rollers run on each rail, each set bearing against the underside of the upper flanges. Four steel cables depeud .. ing from the airship's frame can be made fast to the four sets of rollers and may all be slipped simultaneously. The two rails are so far apart that a dirigible lashed to them cannot be swayed if it has sufficient Uft, and this may be ob ,tained by remOving passengere aad bal Underwears come and under-wears go but “JAEGER” goes on for ever I If you have not yet wintered in Jaeger Underwear, it is never too late to begin. You will thank us later for urging you to it. Seven Weights to choose from Catalogue and Sample8 free on request Dr.' 'Jaeger's S. w. S. Co.'. Own Stores New York : 306 Fifth Avenue, 22 Maiden Lane. Brooklyn: 504 Fulton St. Boston : 228 Boylston St. Philadelphia: 1516 Chestnut St. Chicago: 126 N. State St. Agents in all Principal Cities. Don't stifle your feet as do the old fashioned , emmsy rubbers. They protect the most vital part the sole of the shoe, from cold and damp, and allow the feet to breathe. EVERYBODY NEEDS EVERSTICKS. Always for sale where good shoes are sold ACCEPT NO SUBSTITUTES. “ THE ADAMS S FORD CO. CLEVELAND, OHIO None genuine-without THIS cord. BESrUQWl] More brilliant than electricity or acetylene and cheape; than kerosene. Costs two cents per week. Casts no shadow. Mos. perfect light for stores, factories, churches, lublic halls or the hg!e. Makes and ::rns fts own gas. Simple, durable and handsome. In use in every (1ivilized country in the world. No dirt. No grease. No odor. Over two hundred different styles. Agents wanted everywhere. Write for catalog and prices. THE BEST LIGHT CO. 87 E. 5th St., Canton, O. ROTARY PUMPS AND ENGINES Teir Origin and Development An i m p o r t ant series o f papers giving a h i s t o r i ca l resume of tbe rotary pump and_ engine from 1588 and illustrated witb dear drawings showing the construction of various forms of pumps and engines. 38 illustrati on s. Contained in Supplements 1109. 11 10, 1111. Pr i c e 10 cents e a c h. For .. e by Munn&Co., Inc., and all newsdealers. AIR GAS! Latest Invention srd Vacuum Gas Machine makes gasautomatieallyl Uses97% ordinary air! Cheapest,safest,most hygienic for lighting, heating and cooking! All conveniences of city gas! Non-poisonous non-asphyxiating, inexplosive andin-otiorous! Machine always ready! Gas can be made f orl5c per 1000 cu.f t.! 25 times cheaper than acetylene! Oheaperthan kerosene lamps, electricity or City gas! Saving will pay for the machine in a iew months! Agents wanted everywhere in the United States and abroad! Machine of 2& light capacity, $125.00. Standard-GilletTe Light Co.. 10 H Michigan St., Chicago, U. S. A Broomell's Vacuum Cleaner The “VICTOR" We make a specialty 01 Electric Stationary Vacuum Cleaners fo r residence work. which you can instaH yourself in old or new houses. also Stationary fQ Country Homes for use with Gasoline Engine. and the VICTOR Electric Portable. Send for printed matter. Buy direct and saw money. Victor Cleaner Company York, Pennsylvania Wby not enjoy absolute comfort in your automobile overall kinds of roads t You can accomplish tbjs if your automobile is equipped with tbe The New 1912 FLENTJE Automatic Hydraulic Jounce&Recoil Preventers in a elass by ihelt -»,»-».»» “BEST IN Tlrf WORLD" In a sbort time you will save the cost of the preventers on tires and springs and engine and body of you car. Try a set OD thirty days' free trial aDd three years' guarantee. and be convinced of the correctness of my claims. 15000 a side to any shock absorber manufacturer to disprove that .. Tbe Fleotje ** is the best in the world. For further par ticula rs, app ly to ERNST FLENTJE, 164w Cam bridge St .. Cb, M ... . New Yon Branch: 1926 BVay, c. 6tb St ., Room 400 N. Y. City w Ton B Novemher 25, 1 9 1 1 SCIENTIFIC AMERICAN 485 With our complete line of Waterproofing Products, Dampproofing Compounds, Scientific and Technical Paint Products, we are in best position to solve your problems. A liquid cement coating for stucco, concrete and brick, -applied with a brush. Uniform in color results. Absolutely dampproof. Weather resisting. Does not chip off, crack or peel like paint. Becomes an inseparable part of the wall, sealing all pores and filling hair cracks, giving an artistic flat finish as hard as flint. Walls and Ceilings Finished with ASEPTICOTE Woodwork and ManteL Fi n ished with SNO·WITE TRUS-CON ASEPTICOTE A flat, washable, durable, sanitary, decorative finish for interior walls. Perfectly aseptic and sanitary. Easily cleansed with soap and water. Most artistic in appearance. Manufactured in great variety of tints. Applied on interior surfaces of plaster, cement,brick, wood, burlap and metal. TRUS·CON SNO·WITE An enamel of the very highest quality for finishing interior surfaces of wood, metal, plaster and masonry. Produces a finish with a delicacy of tone, softness, whiteness and luster that cannot be excelled. TRUS.CON INDUSTRIAL ENAMEL A gloss coating of whitest white, with powerful light - reflecting qualities, for treating factories, work-rooms, enclosed light shafts, etc. TRUS·CON FLOOR ENAMEL Produces a tough, elastic and reasonably durable finish on all cement floors, rendering them washable, stainproof, oilproof and dustless. Trus -Con Waterproofing Paste, integral waterproofing for concrete. Trus-Con Plaster Bond, a damp resisting paint for interior of exposed walls. T rus-Con Por.Seal, a transparent coating for dampproofing exterior masonry. Trus·Con Edelweiss, a durable artistic enamel for exterior surfaces. Trus-Con Dairy Enamel, durable, sanitary enamel for dairies and creameries. Trua-Con Laboratory Enamel, to resist chemical gases in laboratories. Trus-Con Bar-Ox, most advanced protective JL coating for iron and steel. Consult us at this time regarding your present Waterproof- When a brisk wmd is blowmg the dlf-ing and finishing problems. We ference between observatory and kiosk can help you. Let us send you II temperatures is le ss than shown by the our litera ture . above compa rison. T he propriety of ar· . tificially ventilating the kiosk-the plan I adopted in a type of kiosk used in Ger· 402 Tr .. ed Concrete Bldg., Detroit, Mieb. l many, as described belo. haa been coft- last during the time that the airship is pushed in or out of its shed. Starting a :ight means simply to take aboard passengers and ballast after the ship is at a safe distance from the menacing walls of the shed, and instantly to release all the hawsers. But entering the shed with a brisk wind blOWing at right angles to its axis and to the rails is more difficult. In this case the ship is halted in the open over the track, pointing into the wind. One of the front cables is fastened to the rollers nearer the shed on the windward rail. With this set of rollers as a fulcrum the ship is worked around by pulling at the rear end, steadying it along the sides, and simultaneously pulling the lee side down, until it becomes parallel to the rails. It is then a simple matter to fasten the remaining cables, unship passengers and ballast, and roll the ship as safely into the shed as though it were a train of railroad cars. It may be worth noticing that this device is the same, though more primitive and stilI depending on the co-operation of a great number of men, as the one suggested in the SCIENTIFIC AMERICAN directly after the accident to the “Deutschland II." Of equal importance to the docking of these big ships is their safe anchoring where there are no sheds. A safe anchorage over unobstructed grounds, mostly parade grounds, has now been prepared near almost every German city. The holding device is a development of the method by which in the past severe squalls occasionally have been weathered. It is different in so far that the pivotal point around which the ship freely swings into the wind's direction is now not on the ground but in the ship's own frame. Even with the short single bow cable formerly used successfully, jerks which strained the frame and the cable were not entirely avoided in gusty winds. (Too much play for the bow in the accident at Limburg snapped the long cable and freed the ship, though it did not damage the frame.) In place of one cable there are now four, giving greater safety. They are part of the ship, and may be seen hanging from the bow. They are fastened to a ring that pivots around a strong pin in the reinforced framework. To anchor the ship, they are made fast with their free ends to four heavy cubes of concrete, each 31 feet in diameter, sunk Into the ground, and so arranged that the four cables evenly radiate toward them from their pivot on the bow. Thanks to its rigidity, the ship now turns around the apex of this pyramid of cabl e s , as smoothly as a new weather vane around a steeple. Unshipping ballast at the bow makes this pyramid very rigid. Weather “Kiosks” at Home and Abroad (Concluded from page 477.) maxtmum and minimum thermometers set, etc., by an employee of the local Weather Bureau station. As a substitute for the iII·exposed and often ill-constructed drug-store thermometer the kiosk amply justifies its existence in providing an accurate record of the conditions to which the urban population is exposed. In hot weather the thermometers in the kiosk read many degrees higher than those of the regular Weather Bureau station. The following comparison of maximum readings during a summer hot spell at Washington is instructive: July, 1911. Weather Bureau Observatory. Kiosk. Degrees Fa h re uh e it 97.7 99.1 96.7 97.8 98.3 95.0 84.2 I Degrees Fahrenheit 105.0 106.5 105.0 104.5 105.5 102.7 93.5 Why Nelson's Is Known As The Perfect Encyclopaedia There Are Four Conclusive and Common Sense Reasons: 1. It Cannot Crow Old because our teIf \2dTlTlOt CjTOW Old subscribers are furnished with at least__________________________________ 500 pages of new information each year-semi-annually, in March and October-which brings them up to the minute on all important events. These pages are properly numbered, and by simply turning a nut in our loose-leaf binding you can remove the obsolete pages. and insert the new. Your Encyclopaedia will be just as much up to date twenty years from now as it is today. No other Encyclopaedia CAN P ...... this feature, as it is fully protected, T russ ed C oncrete 5teeI C o.; 2. Accuracy. 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By-Laws and forms for makinr stock full-paid for cash. property or services. free. President Stoddard. FORMER SECRETARY OF ARIZONA. resident aeent for many thousand cODipanic&. Reference: Any banK in Arizona. STODDARD INCORPORATING COMPANY, BOl 8000 PHOENIX, ARIZONA Veeder Counters to register reciprocatitlg Jnovements or revolutions. Cut full size. Booklet Free. VEEDER MFG. CO. 18 Sargeanl SI., Hartford. Conn. Oyclomete,"s, Odometers, Tachometers. Oo'nte'"s ana ]'ne Oa.tinas. Represented in Great Britain by \IARKT &. Co., LIMI'l'BD, 6 City Uoad, “ibury Square, London, M:c:; Fr:nce, by )AEKT&i o.; LIMITED, 107 Avenue Parmentier, Paris; Germany, Austria·Hungary lind Scandinavian Countrie LUDw. I.QlwB&Co., HutteI StrllSse 17 . 20, Berlin. Price WAN SAFETY FOUNTPEN Is an investment that pays a di'idend 365 days in every year. Always ready to write and never blots or Jeaks RIFE RAM A Water Supply solvES many farm troubles. Have plenty of water without pumpinJ expense or botler jWlt install 'an automatic Rife Ram, !taises “water' DO ft. for each foot of fall -no trouble or pumping expense. Satisfaction Ruaranteed. Booklet, plans, estimate, Free. Rife Engine Co., 2533 T riDity Bdg., N.Y. $36.00 ' e: v-.-A¥:w LANTERN With 01 Improved famous ALeO RADIANT LIGHT This new 191. Model has many improvements and double brilliancy. “Write for illustrated circular of this and Lanterns of all styles and lights at bottom prices. IF YOU OWN A T . ANTERN we should haye your name to Dailtoyou our regular announcements of new slide and lecture sets. '5,000 Lantern Slides to rent. POST CARD MAGIO LANTERN reflects i mage of postcard or an, other picture or object. Prices, $2.75, $12.50, 125.00, $60.00, express paid. WULIAHS, BROWN&EARLE, Inc., 918 Chestirat St.. Philadelphia, Pa., Lantern Dept. 6 Engineering, Microscope, Optical, Scientific, Photo, Lantern Slide Supplies 486 SCIENTIFIC AMERICAN November 25, J9JI IS Christmas suggestion that is new Also oue that you will recognize at once as wonderfully pleasing and timely- C you imagine a more acceptable gilt for a man than a Carborundum Razor Strop or a Carborundum Razor Hone with its remarkable sharpeuing qualities ? - Can you imagine a more appropriate gift for either man or woman than a Carboru'dum octagonal, stag-handled knife sharpener- Or for the sportsman, than a Carborundum sportsman's stone in handsome pigskin case with strap at the back for fastening to the belt ? - Carborundum is the most remarkable sharpening agent the world has ever known-It is intensely hard and sharp-practically crushed diamonds made into sharpening stones for every conceivable sharpening requirement from the honing of a razor to the sharpening of an axe. Put up With Great Care in Handsome Holly Covered Boxes for the Christmas Season and on sale at hardware stores the country over-If your dealer doesn't have them send direct- Don't neglect this new and wonderfully appropriate Christmas offering. No. 79·F Knife Sharpener. octagonal, solid stick of C arborundum, stag handle in neat bo x, - . . .--. . $1.00 No. 78·F Knife Sharpener as above with wooden handle. . .50 No. 103-F Carborundum Razor Hone-very fine andefcient in neat box, 1.00 No. 411-F Carborundum razor strop---heavy weignt, genuine selected horse-hide. razor case handle, trimmed with brass open swivel hardware, 1.75 No. 131-F RoundCombinationStoneforsportsman in ieather case-strap for belt. 1.00 Write today for Carborundum Book - Order Christmas packages The Carborundum Co. Niagara If New York Should Burn? IF New York should burn, like Baltimore or San Francisco, it would bring financial disaster on this entire continent. New York today is considered by engineering and insurance authorities to be in fully as great danger of destruction by fire as were Baltimore and San Francisco before their fires came. The story of the conflagration danger in New York -which, considered as a whole, is growing worse from year to year-is told in a carefully prepared article by Arthur E. McFarlane in the December Number of McCLURE'S MAGAZINE Edited by S. S. McClure Fifteen Cents A Copy Dollar-and-a-Half A Year The McClure Publications, Inc. McClure Bldg., New York sidered. It is a question, however, whether the structure with this modif-cation would answer so well the purpose for which it is intended; since the populace, whose environment the kiosk instruments are designed to gage, does not habitualIy carry an electric fan 3bout the streets, nor even continually wield the palm-leaf in the busy round of daily occupations. On the other hand, neither is the populace inclosed in a cast-iron cage, and possibly finds itself more comfortable in hot weather than would the kiosk thelmometers if they had human sensibilities; so that the question of artifcially ventillating these structures may be regarded as an open one. The meteorological kiosks of Europe, in contrast to those just described, are not maintained by the official meteorological services of the several countries. Some have been erected by instrument-makers, as a means of displaying their wares; others are installed at health-resorts, as an attraction to visitors; but the majority are mere sign-hoards for the display of miscellaneous advertisements, which occupy most of the surface space, the instruments being relegated to any odd corner that can be spared. Their architecture varies according to the taste of the designer, without, as ' rule, any regard to the proper exposure of the apparatus. Some of these structures, especially those erected by the municIpalities, are most imposing-to look at. One built some twenty years ago by the city of Berlin cost 7,000 marks ($1,666). In this structure the instruments were installed behind glass in shallow unventilated panels, and in summer all of them were exposed during part of the day to direct sunshine. The apparatus included a mercurial barometer hung at such an elevation that no one could read it without the aid of a step-ladder. All the instruments were grossly neglected, and those that should have shown identical readings exhibiter instead the most remarkable discrepancies. Latterly, however, certain foreign instrument-makers, especially in Germany, have turned their attention to the production of kiosks satisfying scientific as well as popular and artistic requirements. Probably the first German kiosks to · be cO;lstructed according to scientific princirJlles were those erected in Berlin about 1891 by the Urania Uhren- und Saulen-Gesellschaft, and known as “Uraniasau-len.” (F'ig. 4.) These were intended primarily for displaying advertisements, but contained well.constructed and well-exposed meteorological apparatus, ventilated by a clockwork-driven fan, according to the principle of the Assmann aspira-tien-psychrometer. Unfortunately the Urania Company did not have a long career; the kiosks were bought by the municipality, and in most 'cases deprived of their instruments. In a few, however, the instruments are still kept in operation. Excellent weather kiosks are now manufactured in Germany, though one sees plenty of the :o.pposite kind at the “Kurorte” and other frequented places in that country. The type of kiosk constructed by R. Fuess, of Steglitz, near Berlin, is shown in Fig. 3. This contains a barograph, hygrograph, and thermograph, the pens of which tr3ce their records on a sheet of paper wound around a single revolving drum. The apparatus is vntilated, according to the Assmann method, by a revolving fan, driven by electricity or water-power-usually the latter. Kiosks are also manufactured on a large scale by W. Lambrecht, of Gittingen (Fig. 1) and usually house some of his special instruments; such as the “polymeter” and Ue “weather-telegraph.” The latter oomprises a particular form of hygrometer and an aneroid barometer, the dials of whkh stand side by side; while underneath is a series of diagrams which, it is claimed, enable one to forecast the weather from the indications of the two instruments. The Demand for Young Men in Electrical Engineering (Concluded from page 479.,) nomic principles and a command of those processes of analytical reasoning which can be obtained only by hard study. The graduate who adds judgment and gumption to the qualities derived by the study of the fundamental sciences and Inventors and Inventions A NEW BO O K JUST PUBLISHED BY H. RO BINSON, 41 W. 33rd ST .. NEW YORK. INDISPEN SAB LE AND INTERESTING TO EVERY INVENTOR OR PROSPECTIVE INVENTOR. PROFUSELY ILLUSTRATED. CLOTH BOUND. $1.00. IT TREATS AUTHORITATIVELY IN A CLEAR, POPULAR and ENTERTAINING STYLE THE FOLLOWING SUBjECTS:- How to Invent. Financing a New Invention. Marketing a New Invention. Advice to Inventors. The Glory of Invention. Pictures of Famous ]nventors. Various Ways Employed to Cheat and Rob Inventors. Present Available Means of Protecting an Invention. Treatment the World accords to Them, and Other Important Subjects. EVERY HOME LIBRARY SHOULD HAVE Stories of Useful Inventions By S. E. FO RM AN. author 01 “A History of the United States,” etc Sixteen “ true stories,” stories of human progress as shown in man's making of the match, the stove, and other inventions which are most useful to man in his daily life, told to stir and hold the interest of the young reader. MANY PICTURES. 12mo, 248 PAGES Price $1.00 net, postage 11 cents Published by THE CENTURY CO. New York COMBINATION INDICATING AND RECORDING UNIT OF THE WM. H. BRISTOL ELECTRIC PYROMETERS for high tempfl'lturrs wlth Recorder for installation in Superintendent's office. Write for particulars. THE BRISTOL COMPANY Waterbury, Conn. 150 Chambers Street This “Red Devil” Circular Glass Cutter No. 263 cuts perfect circles from 2 to 22” in window or plate glass. It's the 0 N L Y practical crcular ltand glass cutter made cs a Red Dtil. If yolir dealer Can't furnish it. we will send one prepaid for 11. 25. Smith&Hemenway Co. New York, N. Y. ClaSSl·fl·ed Advertl·Sements Advertising in this column is 7;") cents a lme. No less than four nor more than 12 lines accented. Count ieven words to the line. All orders must be accompanied by a remitTance. BUSINESS OPPORTUNITIES. WANTED PARTY to manufacture my multiple tube pneumatic tire for Automobiles and Bicycles, patented Oct. 17, 191!. A money maker. Kor further particulars address. Dr. Robert B. Gray, Pt. Carbon, Pa. :'NTED :OR EXfOu.-Red earth as used foJ metal cleJing preparations, also Fuller's e:r1h as u:ed for toilet preparations. S;bmit sam;l:s, pri'es and full part,culars. '.O. i, N. Y.;txport, Bo' 773, N. Y. INVENTORS. -Send a copy of your patent to us and we will send you our contracts outlining onr liberal manufrgturi'Y O& er'd J u:ther partLCulars address, Atlantic S'pply Co., Long Branch, J. j. BUSINESS OPP.R'UNITY-Wanted a partner to help manufacture and sril a newly p:tlted autom,bile ac!essory. ;f::ss seller: o;petition. Forfurth!r information address, T. F. Hutcbings, 112 W.52d St. N.Y. GEr BUSY—Lear'! h' gre:t talmer :l:tem of making nam i ilates, house numbe:, sI;:s, etc. :ake $15.00 a day. Sendfor eutiful thirty-two p"e Jg?J - Sixty· five illustratfg ; s. E. E. Pa1ier, Wooster, Ohio. FOR SALE. LOCAL REPRESENTATIVE WANTED.-Splendid income assured right man to act as our representative after 'arnmg our business thoroughly by maiJ. ['ormer experience unnecessary. All we require is honesty, ! bility, ambition and wUlingnets to learn a lucrative busi-ness. No soliciting or traveling. 'his is an exceptional opportunity for a man in your section to get into a big paying business without capital and become indepen -ent for lite. Write at once for ful] particulars. Address E. R. Marden, Pres .• The National Co-Operative Real Estate Company, L 378 Marden Building. Washington, D. C. _________________ OLD COINS. .LD COINS.-$7.75 paid for rare date 1853 quarters. $20 fot a $ %. Keep all money dated before 1884, and send lOco at once for New Illustrated Coin Value Book. “x 7. It ma y mean your fortune. Clark&Co., COin Dealers, Box 45, Le Roy, N. Y. PATENTS FOR SALE. FOR SAL E.-Patent No. 999,948. New mechanism for clutches. Patent applied to 9 pulle ys, but not exclusive, cheapest; most positive wear adjusting clutch made. Have working model. B. W. Beall, Lansdale, PR. PATENT FOR SALE, No. 983.775. Fire Esc m pes. issued Feb. 7, 1911. for copy of same can be obtained from Victor J. Evans, patent office. For further particulars write C W. Scbumann. Newell, S. fak. REAL ESTATE. TEXAS INVIlST:ENTS.-Buy farm orcbard garden landg near Houston, the greatest and most prosperous city in the southwest, where values are ,oing up all the t:!e and f mrtun:: sa'e in re:l est:ie in sgort wb' re. Easy terras if desired. Single crop pays for Jand; several crops annually. Address E. C. Robertson, 501 Kiam Bldg., Houston, Tex. WANTED. W::T!D.;gne mech"nical er§ineIf t t $£500 Oer annum. f competit:; exa:inatiP will be held Ee: cember 1 8, 1911, at the Uv. S . 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Order from your newsdealer or from MUNN&CO., Inc. 361 Broadway, New York THE SCHWERDTLE .SMP CO. iSTEEL STAMPS LETTERS&FIGURES. BRIDGEPORT CONN. Models&Experimental Work INVENTIONS DEVELOPED SPECIAL MACHINERY . . . E. V. BAILLARD CO., 24 Frankfort St. N Y. TFTjpTTTnjJI COllies Kn.srines, Blwers and Hot t lors' Machmery uh “ VILTER MFG. CO. 899 Clinton Street, Milwaukee, Wis. m BUBRICATisVoT II ANYIN frG •wm ...I 118.124 Uoi-th Clinton Sfe* CH B [s LVa co. ftf msffl S§f A Learn Watchmakl-ng We reach it thoroughly in as many courns as it fOrI!rl; tfcok yeatp. 1) >es awa:Vr ith tedio;;t apprenticeship. Money earner while stud,llg. PositioIl.; secured. Kasl terms. Send for CHtltog. lT. I.I'{IS WATCHMAKING SCHOOL. St. I..011U1, Mo. MASON'S NEW PAT. WHIP HOIST for Outrigger boists. Faster tban EIevators, and hoist direct from teams. Saves b·and.lii>g art le;s expense [anfd. hy VOLNEY W. MASOa&(0.. Jnc, l'rovldellce. 1. I., IJ. t*. A. ~*rint Your Own ) OmK ,ircnI3rs, books. neW'!loper. gress *5, Lager i(^s^-0 t~r^~s> ^lb, Rotary $h(. Ra\'e money. Bis; profit pnnting; i ^SK^HnlBc^S fOl' others. All easy, rnips sent. \rite factory for pTres E ^S%j£Xdollar;£.&olnc(tieut ELECTRICMOTORS SPECIAL Grinders MACHINES Polishers ROTH ELECTRIC MOTORS 198 Loomis Street. Chicago, Ills. C R U 0 E A S B E S T 0 S DIRECT FROM MI NES R. H. MARTIN, OFFICE. ST.PAUL BUILDING 220 B way, New York, PREPARED ASBESTOS FIBRE for Manufacturers use economics laid down in such a course has the assurance of being in demand as long as this country remains a great industrial nation. Tn these days, when the industrial needs of tho land are grovdng so rapidly, the demand for electrical engineering graduates who come from the best planned and administered engineering schools is very great, and, as long as the industrial growth of the nation continues, the demand will continue to absorb all well trained young men that the schoo Is can supply. An experienced engineer should have the ability to conceive, originate and direct extended industrial enterprises. To attain this ability requires many years of mature experience, and an electrical engineering course that is expected to promote the highest welfare of its graduates must be largely occuTned WIth teaching the principles of science, i. e., the purport of known natural laws and their relations to each other. Young men \ith th1' 8 sart a f a traI' nIng are no t seasoned engineers, but they have the training which gives them great rapacity for becoming engineers and after sufficient exverience in actual practice of obtaining the hIghest rank consonant WIth the1r Individual abilities . This great ca]),acity for becoming effidcnt engineers through th e season .ng e ffee t 0 f exper'en., whIC h engineering graduates ]OSSeSS, is a suffic.ent reason for th 81'r b8l'ng In demand. 8nch graduates have opportunities for professional usefulness in many branches of electrical engineering. In telephony the work is primarily OM of unending detail; but it may lead to broad and comprehensive executive duties in connection with OIle of the great servants of commerce, and the telephone service offers so many opportunities of benefiting the ]ublie that it has attracted a great many able men to its ranks. Tn electric railroading is found a rapidly growing branch of service that appeals to the imaginations of many. 'here are opportunities In it leading to executivH duties in a branch of industry that composes the very bacldJOne of commerce. With the present tendency toward electrifcation of the great terminals and mountain divisions of trunk line steam railroads and even of their main stems, the graduate of an electrical engineering course who goes into railroading with the f,'m purpose of learning the best processes of handling traffic has possibilities of a great career before him. ; Similar attractions are found in electric light and electric power transmission, and attractions of other kinds and unending variety are found in the manufacturing industries; but it should be remembered that most of the men capable of deserving the highest positions within the sphere of electrical engineering practire must expect to become either men of executive force or men who originate new projerts or machines. In either of these vocations it will be found that far more than a trades education is needed and that the a PPl'opri ate ed 1 cation must be, broadl y speaking, the education o f a gentleman, a man of the world, and a scientist. Such men find use for all of the scientific studies already named and also for the training in language, history and political science which ha- now come to an honored place in the curricula of a few of our engineering schools. There is also at the present tinlB a conSI derable call for competent teachers in electrical engineering courses, and the work of research in regard to electric and magnetic phenomena is growing rapidly and is calling for workers. When the field of electrical engineering is examined in this manner, and the experience of the able young men who are now graduating year by year from the electrical engineering schools is compared, there can be no other conclusion reached than that electrical engineering as a profession offers opportunities for those who have industry and a taste for science and business which are not excelled in any profession or branch of business. Experience shows that there are opportunities in electrical engineering for all well trained young men who possess good sense and industrious habits, and particularly for those who have the ambition, capacity and industry to digest a course at one of those few schools which stand in the first rank of scientific accomplishment and earnest en· , deavor. His Excellency Prof. Dr. Von Leyden Tureeier }'"':*! >1e.V,el <l,,uc., Deri,,i Cucertit.e, uritn. "I have gladly and frequently prescrIbed Sanatogen in cases 01 delicate patIents in my clinical as well as my private practice and am extremely satisfied with the results." Late King Edward's Physician, Dr.Ernest Ott 1rlte8" HI have been us 01 g Sanat?gen lor b number of years II my practice wIth excellent re-sults. These resu Its have been notably goodin the case ol eld-erlypeople when it was desir?le to build up the stlength, t h stimulate the bodily lunctions, and to Improve the Clrculation 01 the blood." Prof. C. A. Ewald f fieri,,,, niren;t, Heeler iereerie e,re” ,//,, ile^klue MeelieeU tie/me,!,,',, "I can say that I have used Sanatogen in a gJeat number of cases (that is, i n those dist!,bances ol m! t:'° o li s m which w ere main ly of a nelV' ous or neurasthenic ori:in), and h: ve ' b:a?: ;j excellen; .. sults. “ P ro f. T ho mas B . Stillman, M.S., Ph.D. 'li,: ,r,M-l,mi ,,!, ,:l,e,-ietef Steeeu^ LtetitiUe, writes: "The chemical union of the constituents of Sanatogen is a true one, representative of the highest skill in the formation of a product containing phosphorus in the organic phos pbate condition, and so com bined that digestion and assimilation of Sanatogen are rendered complete with the greatest ease ." B “ Physicians in Many * Lands Advise—Sanatogen ILL HEALTH has no nationality and SCIence has no geographic boundaries. When 15,000 physicians (in Germany, England, America and elsewhere) endorse Sanatogen over their own signatures-when 120 articles in leading medical journals of these countries extol the virtues of this remarkable food-tonie-there can be no exaggeration in calling Sanatogen an international scientific triumph. Wherever the movement of civilization is swiftest the toll on the nervous system is greatest-and no nation escapes the toll. The remarkable fact that Sanatogen is today the most popular international food· tonic shows first the need of it; second its splendid ability to meet that need. Sanatogen, the food-tonic, speaks in the universal language of the human system. To the cry of tired nerves it answers in a way the nerves understand-its elements are the very elements of human strength. Its pure albumen and sodium glycero-phosphate, scientifcally combined, restore to nerves and cells and tissues the elements taken from them by the drain of overwork and worry. Its vitalizing, nourishing, upbuilding action gladdens every fibre of the system, heIps to give back to man his dominion over his body. Noted men of many nations join with the exponents of science in acknowledging the unique powers of Sanatogen-for it is by resulls that Sanatogen has earned its undoubted pre.eminence. Do you need upbuilding ? If you do, you need Sanatogen. Sanatogen is sold by all leading druggists at $1.00, $1.90 and $3.60 W ri te f or a FREE co py o f “ Ou r Ne rves of Tom or ro w “ The w ork of a physicia n- aut ho r. writte n in an abs orbi n gly inte restin g styl e, b e a utifully ill ust ra te d, and c o nt aini n g f acts and info rmati on of vi t al interest to yo u. Th is b o o k a lso co n tain s ev idenc e of the value of Sanatogen which is as remarkable as it is conclusive. Gel Sanatogen from your druggist-if not obtainable from him, sent upon receipt 0/ price. THE BAUER CHEMICAL COMPANY 515 Everett Building Union Square New ¥ork JUST PUBLISHED J .I :ew and A uthorilalive $ook **^°%. MONOPLANES and BIPLANES THEIR DESIGN, CONSTRUCTION&OPERATION The Application of Aerodynamic Theory, with a Complete Description and Comparison of the Notable Types By GROVER CLEVELAND LOENING, B.Sc, A.M. Aviation is a predominant topic in the mind of the public, and is rapidly becoming one of the greatest goals of development of the progressive engineering and scientific world. In the many books that have already been written on aviation, this fascinating subject has been handled largely, either in a very “popular” and more or less incomplete manner, or in an atmosphere of mathematical theory that puzzles beginners, and is often of little value to aviators themselves. There is, consequently, a wide demand for a practical book on the subject-a book treating of the theory only in its direct relation to actual aeroplane design and completely setting forth and discussing the prevailing practices in the construction and operation of these machines. .. Monoplanes and Biplanes” is a new and authoritative work that deals with the subject in precisely this manner, and is invaluable to anyone interested in aviation. Mr. Loening, who has come in intimate contact with many of the most noted aviators and constructors and who has made a profound study of the subject for years, is unusually well informed, and is widely recognized as an expert in this line. In a clear and definite style, and in a remarkably thorough and well.arranged manner he has presented the subject of aviation. The scientific exactness of the valuable data and references, as well as the high character of the innumerable illustrations and diagrams, renders this work easily the best and the most useful, practical and complete that has ever been contributed to the literature on aeroplanes. Following is a table of the contents: PART I. The Design of Aeroplanes. Chapter I. Introduction. II. The Resistance of the Air and the Pressure on NOlal Planes. III. Flat Inclined Planes. IV. The Press",e on Curved Planes. V. The Frictional Resistance of Air. VI. The Center 01 Pressure on Flat and Curved Planes. VII. The Effect 01 Depth 01 Curvature and Aspect Ratio upon the Lift and Drilt of Curved Planes. VIII. Numerical Example of the Design of an Aeroplane PART II. Detailed Descriptions 0/ the Notable Aeroplanes. Chapter IX. IntlOduction. X. Important Types of Monoplanes. X . Prominent Types of Biplanes. PART III. Comparison of TJpes. XII. Comparison of the Prominent Types. XIII. Controlling Apparatus. XIV. Accidents. XV. The Varable Surface Aeroplane. Index. 12mo. ( 6x8> inches) 340 Pages, 278 Illustrations. Attractively bound in doth. Price $2.50 net, postpaid A n illustrated descriptive circular wil be sent free on application. MUNN&COMPANY Inc. Publishers 361 Broadway New York 488 SCIENTIFIC AMERICA November 25 , 1 9 1 1 THE YOUTH'S CON F YOUR FAMILY is worth the best you can give in house and food and clothes, is it not worth the best reading as well? And the best of reading -best for boy and girl, best for men, best for women -is contained in the pages of The Youth's Companion. ::::::: All Remaining 1911 Issues Free. for 1912 HOW TO GET THEM EVERY NEW SUBSCRIBER who at once cuts out and sends this slip (or mentions this paper) with $1.75 for the 52 issues of The Youth's Companion for 1912 will receive Free ALL THE ISSUES for the remaining weeks of 1911, including the Thanksgiving and Christmas Holiday Numbers; also Free THE COMPANION PICTURE CALENDAR for 1912, lithographed in 12 colors and gold - an extra copy being sent to every one making a gift subscription. THEN THE YOUTH'S COMPANION for the 52 weeks of 1912 _II for $1.75. Your last chance to get The Youth's Companion at this price. On January 1, 1912, it will be advanced to $2.00. THE YOUTH'S COMPANION, BOSTON, MASS. R EADING which with all its pOWer to entertain is a power also to benefit. Here is a handful out of hundreds of Companion contributions for 1912: The Brotherhood of Boy Scouts Lieut.-Gen. Baden-Powell General Booth William T. Stead Humorous Incidents of the Gridiron Walter Camp When Jack Writes Home Frank T. Bullen The Exacting Daughter Harriet Prescott Spofford The Safety of the Ship William H. Rideing Axel Eriksson, the Great South African Hunter Sir Harry Johnston The Main Elements of Success President Maclaurin of the Mass. Inst. of Technology A Tribute to Dickens Jerome K. Jerome The Struggling Student in Scotland Sir James Crichton-Browne Student Ideals in Japan and America President Pritchett of the Carnegie Foundation Then there are the stories, nearly 300 of them-stories different from the common lot. Stories of pluck in adversity, coolness in peril. Stories of the sea and the waste places of the earth. Stories of life among the Indians. Stories of the Awakening of character. Droll sketches of domestic trials and vicissitudes. You'll like them all. Send for our 1912 Annnouncement, free. A History tle American People In Five Volumes By WOODROW WILSON PLD., Litt.D., LL.D. Former President of Princeton Unilersity THE annals of historical iiterature record no more brilliant and masterful piece of writing than Woodrow Wilson's epoch-making work in five volumes-A History of the American People. Governor Wilson has devoted the best years of his life to the preparation of this great work. It is monumental in character and scope, and represents the genius of the greatest historical writer of the present time. It is written in that delightful, fowing sty Ie which translates historical facts into the romance of a nation. In the matter of illustration every feld of human activity has been searched, and hundreds of new portraits, prints, maps in color, plans, and pictures make the pictorial features alone tell their wonderful story of the birth and growth of what is now the United States. The five large octavo volumes are printed on special paper and splendidly bound in dark - blue cloth with gold lettering. We will send you the entire set of five volumes, all charges prepaid, on HARPER& Ns. receipt of $1.00, and enter your name as a subscriber for both HARPER'S BROTHERS >\ MAGAZINE and HARPER'S BAZAR for one year, at no additional cost to ^Ne'wVoT'e N\ you. If you do not like the books when they reach you, send them back at our expense and we will return the $1.00; If you do like them send us $1. 00 every month for eleven months. 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MASON, author of “The Four Feathers,” “The Broken Road,” etc., bcgan in the October number Robert Grant's CONVICTIONS OF A GRANDFATHER The changed social, political, and living conditions are dwelt upon, the question of the accumulation and uses of great fortunes, the increased cost of living, divorce, woman suffrage-almost everything of vital and familiar interest PRICE COLLIER, whose “England and the English from an American Point of View n was a real literary sensation, will later in the year begin a series of papers along similar lines upon GERMANY AND THE GERMANS The Traces and Influences of France in the Settlement of America, by PRESIDENT FINLEY. The romantic and wonderful story of the settlement and growth in civilization and power of the great Middle West, the marvellous changes that have followed in the footsteps of the old French explorers-La Salle, Marquette, Joliet, and others SENATOR HENRY CABOT LODGE will be represented by a group of articles giving his REMINISCENCES OF EARLY DAYS THE WITCHING HILL STORIES by E. W. HORNUNG, creator of the incomparable Raffles, past master of the short story of mystery and adventure A most remarkable and fascinating series of experiences in a London suburb Early in 1912 will begin THE HEART OF THE HILLS, a new novel by JOHN FOX, Jr. Have You Seen the 1eautffu( <brfstmas $.crfbner 1 If you have not already sent your subscription, send it now and begin with October to secure the first chapters of Mr. Mason's story. A PROSPECTUS for 1912 will be sent free upon application. Three Dollars a Year Twenty-five Cents a NUlber CHARLES SCRIBNER'S SONS, NEW YORK