By far the most important ships building for our navy to-day are the two big battleships “North Dakota,” under construction at the Fore River yard, and “Delaware,” now building at Newport News, Va. These ships, to use the current phrase, are the “answer” of the United States to the battleships of the “Dreadnought” type, which are being constructed for other navies. On the cover of this issue is a drawing of the “Delaware,” which gives a good impression of her lofty freeboard, great length, and formidable fighting qualities. These ships are a great advance upon the “South Carolina” and “Michigan"; for in them it was possible to remedy the defects of low freeboard and low speed, while the battery is greater by two 12- inch guns and a powerful secondary battery of 5-inch pieces. Furthermore, the great displacement of these ships has made it possible to give them an amount of armor protection never before approached. The speed has been raised to 21 knots, and the bunker capacity is also very large. The system of mounting all guns on the center line of the ship, adopted in the “South Carolina” and “Michigan,” has been followed, with the result that their broadside fire is twenty- five per cent greater than that of the “Dreadnought,” and will probably equal that of any battleship afloat at the time they will go into commission. The ships will be 510 feet on the waterline, 85 feet 2% inches in maximum breadth, and will displace on trial 20,000 tons on a mean draft of 26 feet 10%, inches. On trial they must carry 1,000 tons of coal in bunkers whose total capacity is 2,500 tons, and the speed must be 21 knots. The “Delaware” and her sister follow the “Dreadnought” type, in having a long forecastle deck extending from the bow to about the center of the ship. The main deck, below this, has the same free-1 board as the “Connecticut,” or say about 20 feet. The forecastle deck has a freeboard of 28 feet. The 12-inch guns are mounted as follows: Forward is a two- gun turret, with the axes of its guns 24 feet above the waterline. Close abaft of this, with its barbette of sufficient height for the guns to clear the roof of the forward turret, is another turret, carrying two 12-inch guns. Immediately abaft the break of the forecastle deck are two two-gun turrets, the guns of the forward pair firing over the roof of the after pair. These guns, like those on the forecastle deck, are located on the axis of the ship. Abaft is the fifth turret, so placed that its guns have a command of 24 feet above the waterline. It will be seen from this description how excellently are placed the guns of the main battery. Four of them have a command of 24 feet, four of 30 feet, and I one pair, the second pair from the bow, is carried at a height of about 36 feet above the water. The battery of fourteen 5-inch guns for repelling torpedo- boat attack is mounted in broadside; two of the guns forward in the bow in spon- sons, so arranged that each has a slight arc of fire across the axis of the ship. Two others are mounted astern on the gun deck, and the other ten in broadside in a central battery. The armor protection is unusually complete, superior even SUBMARINE SIGNALS FOR SUBMARINES SUBMARINE SIGNALS, as installed on the Octopus and CuttlefisA, are the only means whereby submarine boats can always keep in communication with their tenders, both sending and receiving such signals at distances up to five miles or more SUBMARINE SIGNAL- COMPANY BOSTON, MASS., ..nd .LONDON, ENGLAND BREMEN : Norddeutsche Maschinen- und Armaturen-Fabrik, Agents The Mietz&Weiss Marine and Stationary Oil Engines Used in the United States and Most All Foreign Navies to that of the “South Carolina” and “Michigan.” The belt is 11 inches thick by 8 feet in width, and above it the side of the ship is protected by a secondary belt 7 feet 3 inches wide and 10 inches thick. These two belts afford a reasonable assurance of the maintenance and stability of the ship under battle conditions. Above the main casemate armor, amidships, the side is protected by 5-inch armor, behind which are mounted ten of the 5-inch guns. This armor also affords protection to the bases of the smoke- pipes. The percentage of weight allotted to hull and armor in these ships is considerably greater than the percentage of such weights allotted to similar purposes in the largest battleship now afloat. The contract speed is 21 knots, and this is to be obtained in the “Delaware” by reciprocating engines, and in the “North Dakota” by turbines of the Curtis type. Operate on Kerosene Oil, Fuel Oil, Alcohol, Crude Oil and Distillate. Stationary, I to 150 horse power; Marine, I to 120 horse power. Over 40, horse power in operation. Send for catalogue. August Mietz Iron Foundry&Machine Works, 128-38 Mott St., New York WITTE GAIOLAKE ENGINES Positively beyond .ill question of a doubt, the highest type of perfection yet attniued iu modern gas engine construction. Everv one bu:lt and guaranteed fully capable of developing horse- =t*Sed Five “-Year Bond Guarantee. £ kerost'i.e distillate or alcohol. New features: exclusively Bensonized bronze bearings: self- cleni)in<r electric igniter; vertical self-wating valves; aniomatic wipe oilers. .All parts iuter- changeableand adjwst&bie.Quickdeliveries.Write toil:t\ forde:riptivecatalog “Y"and prices, WinE IRON WORKS CO., 546 West Fifth Street, Kansas City, Mo. NEW PAPERS ON Concrete, Reinforced Concrete, and Concrete Building Blocks SCIENTIFIC AMERICAN SUPPLEMENT 1543 contains an article on Concrete, by Brysson Cunningham. The article clearly describes the proper composition and mixture of concrete and gives the results of elaborate tests. SCIENTIFIC AMERICAN SUPPLEMENT 1538 gives the proportion of gravel and sand to be used in concrete. SCIENTIFIC AMERICAN SUPPLEMENTS 1567, 1568, 1509, 1570, and 1571 contain an elaborate discussion by Lieut. Henry J. Jones of the various systems of reinforcing concrete, concrete construction, and their applications. These articles constitute a splendid text book on the subject of reinforced concrete. Nothing better has been published. SCIENTIFIC AMERICAN SUPPLEMENT 997 contains an article by Spencer Newberry In which practical notes on the proper preparation of concrete are given. SCIENTIFIC AMERICAN SUPPLEMENTS 1568 and 1569 present a helpful account of the making of concrete blocks by Spencer Newberry. SCIENTIFIC AMERICAN SUPPLEfENT 1534 gives a critical review of the engineering value of reinforced concrete. SCIENTIFIC AMERICAN SUPPLEMENTS 1547 and 1548 give a resume In which the various systems of reinforced concrete construction are discussed and illustrated. SCIENTIFIC AMERICAN SUPPLEMENTS 1564 and 1565 contain an article by Lewis A. Hicks, In which the merits and defects of reinforced concrete are analyzed. SCIENTIFIC AMERICAN SUPPLEMENT 1551 contains the principles of reinforced concrete with some practical illustrations by Walter “..oring Webb. SCIENTIFIC AMERICAN SUPPLEMENT 1573contains an article by Louis H. Gibson on the principles of success In concrete block manufacture, illustrated. SCIENTIFIC AMERICAN SUPPLEMENT 1574discusses steel for reinforced concrete. SCIENTIFIC AMERICAN SUPPLEMENTS 1575, 1576, and 1577 contain a paper by Philip L. Wormley, Jr.( on cement mortar and concrete, their preparation and use for farm purposes. 'The paper exhaus- discusses the making of mortar and concrete, depositing of concrete, facing concrete, wood forms, concrete sidewalks, details of construction of reinforced concrete posts, etc. SCIENTIFIC AMERICAN SUPPLEMENT 1586 contains a review of concrete mixing machinery hy William L. Larkin. SCIENTIFIC AMERICAN SUPPLEMENT' 1583 gives valuable suggestions on the selection of Portland cement for concrete blocks. SCIENTIFIC AMERICAN SUPPLEMENT 1581 splendidly discusses concrete aggregates. A helpful paper. SCIENTIFIC AMERICAN SUPPLEMENTS 1595 and 1596 present a thorough discussion of sand for mortar and concrete, by Sanford E. Thomson. SCIENTIFIC AMERICAN SUPPLEJiIENT 1586 contains a paper by William L. Larkin on Concrete Mixing Machinery, In which the leading types of mixers are discussed. SCIENTIFIC AMERICAN SUPPLEMENT 1626 publishes a practical paper by Henry H. Quimby on Concrete Surfaces. SCIENTIFIC AMERICAN SUPPLEffiNT 1624 tells how to select the proportions for concrete and gives helpful suggestions on the Treatment of Concrete Surfaces. ' SCIENTIFIC AMERICAN SUPPLEMENT 1(134 discusses Forms for Concrete Construction. SCIENTIFIC AMERICAN SUPPLEMENT 1639 contains a paper by Richard K. Meade on the Prevention of Freezing in Concrete by Calcium Chloride. In SCIENTIFIC AMERICAN SUPPLEMENT 1605 Mr. Sanford E. Thompson thoroughly discusses the proportioning of Concrete. SCIENTIFIC AMERI CAN SUPPLEMENT 1578 tells why some fail in the Concrete Block business. SCIENTIFIC AMERICAN SUPPLEMENT 1608 contains a discriminating paper by ROSS F. Tucker on the Progress and Logical Design of Reinforced Concrete. Each number of the Supplement costs 10 cents. A set of papers containing all the articles above mentioned will be mailed for $3.40 Order from your Newsdealer or from MUNN&CO., PUBLISHERS, 361 BROADWAY, NEW YORK CITY WARSHIP TONNAGE OF THE PRINCIPAL NAVAL POWERS. (Continued from page 414.) what is, after all, the most important point of all, namely, the personnel. It i' not so much the gun as the man behim, the gun that determines the issue. It L not so much the speed and cruising radius of the ships, or the judicious emplacement of their batteries, or their handy maneuvering qualities, that determine the issues of a campaign, as it is the efficiency, prudence, dash, and all- round genius of the officers who fight the ships. Moreover, in order to get the best results out of a fleet, not only must the personnel be of the highest efficiency, but it must be sufficiently adequate in numbers; for modern wars have shown that, in tqe wear and tear of a bitterly-fought conflict, there is nothing that calls for a larger reserve than the personnel, both officers and men. Hence, the great significance of the comparison of the personnel shown on the accompanying diagram. Tho results are striking, and certainly, for th.- United States, very disconcerting. Although in the number and displacement of our ships we stand second on the list, in the number of enlisted men we stand last; far below Japan, whose total tonnage is not more than about sixty per cent of our own. With a total tonnage of 611,616 against Japan's tonnage of 374,701, we have only 18 flag officers against Japan's 55; 182 captains and commanders, against Japan's 245; 751 other line officers and engineers, against Japan's 1,751; and 34,062 enlisted men, against Japan's 41,070, Germany's 42,400, France's 51,926, and England's 98,973 enlisted men. THE UNITED STATES NAVAL ACADEMY. (Continued from page 41-5.) curring. The baseball and football games of the midshipmen are of intense intcrer.f to the officers. For exercise there is goif and tennis, and some ride. All in all, it is a pleasant, interesting life. MIDSHIPMEN: APPOINTMENT AND ENTRANCE. Appointments to the Naval Academy are made by representatives and senators, and to a very limited extent, by the President. Presidential appointments are generally given to the sons of army and naval officers. Sometimes congressional appointments are given in accordance with the results of competitive examinations, but not generally. For appointment the candidate must be between sixteen and twenty years old. Physically he must be free from any chronic defect. Mentally he must pass an examination in grammar, geographv, United States history, world's history. arithmetic, algebra, and geometry, so severe that half of the candidates fail. THE ORGAXIZATJOX OF THE M IDSHIP3! 1-:". The midshipmen are organized as a naval brigade. The purpose of this h twofold. First it gives a perfect control individually over each one of the eight hundred and fifty midshipmen. Collegians live pretty much as they plf'ase and how they please, and come and go as they may desire. They elect to take DECEMBER 7, 1907. s certain studies, and later cut lectures if they so please, and are not required to give a very complete account of themselves. But the eight hundred and fifty midshipmen at Annapolis all go to bed at the same time, ten o'clock, and get up at the same time, six o'clock. They all live in rooms exactly alike, with furniture after the same pattern. They march to and from meals together, to and from recitations together. Should a midshipman be absent from any assembly or formation where he is due, it will become known instantly, and the cause of his absence will be ascertained. At any one time all midshipmen will be dressed exactly alike; if one midshipman is wearing rubber overshoes, all will be. Midshipmen of one class all study exactly the same lessons each day, and recite on them in the same periods. Study hours and recitations occupy the midshipman until half-past three, and drills take place between 3: 40 and 5 P. M. On a particular day twenty different kinds of drills may be going on in all of the different departments. In light of the foregoing, it is seen that a most intimate personal control of each midshipman is necessary, and their organization into a naval brigade effects this. If there was not this intimate control, if there was not a complete hold on each midshipman all of the time, there would be lost an incalculable amount of time if nothing else. But there is something else this organization effects; as previously said, its purpose is twofold. This second purpose is the effect upon the character of these young men. Each midshipman must constantly every day account for himself to some. ' one higher up in authority than himself. Unconsciously he acquires the habit of taking great pains to learn what his exact duties and responsibilities are. As a midshipman he learns the meaning and necessity of regulations and discipline. When he enters these terms have no more meaning to him than are obtained from dictionary definitions. He is then bewildered with the multiplicity of rules that regulate his life. He learns their necessity by hard knocks, by punishment for ignorance or violation of them. When he graduates, four years later, these regulations are part of his being, his whole personality is saturated with them. He then reports aboard ship and finds the same spirit controlling the ship that he had become so used to. As a result he instantly feels at home, he knows the regulations that control his own action, and he knows how to apply and enforce the regulations upon the enlisted men that come under his authority. A most important quality required of the naval officer is the habit of command. This can never be learned from books, and the man who can successfully command must also know how to obey. The four years' life of the midshipmen at Annapolis is a life of obedience. In the last year, in addition, the midshipman begins to acquire the habit of command; under the direction of the commandant and his assistants, the discipline officers, the brigade of midshipmen is officered and controlled by the senior classmen. And so perfectly is this done in spirit and practice, that the authority of cadet officers is no more questioned by the midshipmen than is the authority of the officers aboard ship by enlisted men of the crew. The brigade is commanded by the cadet commander. It is divided into two battalions, each commanded by a cadet lieutenant commander. Each battalion is composed of six companies, commanded by cadet lieutenants, assisted by cadet junior lieutenants, . and cadet ensigns. The companies are further divided into crews, comnded by cadet petty officers. Each of the cadet officers has particular and responsible duties in connection with the midshipmen under his direct orders, and the sequence of authority is swift and certain. The brigade of midshipmen is, under the commandant's direction, a self-controlled body. A discipline officer is al ways present at the different formations, but he is never required to do more than give an order in a quiet tone to the senior midshipman present. In carrying out inspections, in enforcing regulations and reporting infractions thereof, the discipline officers are always assisted by the cadet officers. It is the hearty co-operation of these that is depended on, and that counts much toward sustaining the high standard of duty and honor that animates the brigade collectively and midshipmen individually. This co-operation exists and is effective, and the writer is glad, to record his appreciation of the earnest efforts of these splendid young officers. STUDIES. Instruction at Annapolis is given on the personal recitation system. Each class is divided into sections of about ten men each. There are three one-hour recitations each day. With so few in a section, each midshipman gets much personal instruction. The first two years' book work is not naval in character. It is principally composed of mathematics, but also includes the study of rhetoric, naval history, physics and chemistry, mechanical drawing, and French and Spanish. As far as these studies are concerned, they might be pursued in any educational institution, perhaps with as good results as at the Naval Academy. This preliminary mental training is necessary before the work in the professional scientific branches is commenced. But outside of these studies in the first two years of his course, the midshipman has invaluable training in the various daily drills, in naval organization, and in the naval spirit and discipline that envelop him. In the last two years the studies are entirely professional. The time is devoted to seamanship, navigation, marine and electrical engineering, ordnance and gunnery, naval construction, and kindred subjects. The different department drills keep pace with the subjects taught in the class rooms, and as far as possible are allied to them. DRILLS. The scheme of the practical exercises is planned with reference to the class the midshipman is in. As a fourth-class man he will be a rear-rank private, pull an oar in a boat, haul on ropes and personally furl sail, occupy the most unimportant great-gun station in a turret, and fill an ordinary seaman's billet on the summer practice cruise. As a first-class man he will occupy a position of responsibility in these drills, will receive instruction himself and at the same time will assist in instructing the lower classmen. These drills are of great variety. The purpose is that when a midshipman is graduated and sent to a cruising ship, he will himself have performed every kind of work required of the enlisted man, and thus he can instruct the latter. The drills are in dancing, boxing, fencing, building and managing steam and electric machinery, target practice with small arms and great guns, artillery, infantry, torpedoes, signals, tactics, boat sailing and rowing, and seamanship, both in steam and sailing vessels. Modern war vessels take the midshipmen on an oceangoing practice cruise each summer, where each midshipman is initiated and practised in duties suitable to his state of progress. As a senior classman he will have the duties of a ship's officer. PRIVILEGES Axn CUSTOMS. Privileges depend upon class rank and conduct. The first-class man has freedom of liberty to Annapolis to a greater extent than is accorded the fourth-class men. Midshipmen are graded in one month according to the number of demerits assigned the previous month. There are three conduct grades. A midshipman receives fifty demerits if he wears non-regulation clothes, and would receive fewer for a less serious offense, three for instance for being late to formation. Midshipmen are much influenced by class sentiment. Speak unkindly of a DECEMBER 7, 1907. SORE THROAT To prove the Efficiency of Hydrozone to Sore Throat Sufferers, I will send One 25 Cent Bottle Free to anyone mentioning this paper and sending 10 cents to pay postage and packing. Hydrozone is a harmless germicide, indorsed and successfully used by leading physicians. Not genuine without my signature on label. Ask for Booklet on Treatment of Diseases. Sold by Leading Druggists. Chemist and Graduate of the “ Ecole Centrale des Artes et Manufactures de Paris” (France) Dept. V. 63 Prince Street, New York Dealers Wanted Everywhere Build It Yourself Any boy or amateur can build this perfect little 1 H. P. veitical, '2 cycle gasoline engine on a foot power lathe from rough castings Ly following our simple blue pr.nt working' drawings. Others are doing it. so can you. No engine equals it for simplicity.. strength and durability. Fills every requirement wherelig'ht moti; power is needed. Wn'te for bookiet aud prices on castings and finished engines. GARDNER MOTOR COHPANY 6011 Delmar Ave., St. Louis, U. S. A. Keystone Well Drills for Artesian and Ordinary Water Wells; Mineral Prospectiog and Placer Testing for Dredgers ; Deep Drilling' for Oil and Gas; Contractor's Blast Hole Drilling, River and Harbor Exploration, etc. Our five catalogs are textbooks on these subjects. KEYSTONE WELL WORKS Beaver Falls, Pa. New York Office,- 170 Broadway LEN S E S Besides making all kinds of PHOTOGRAPHIC LENSES we manufacture to order lenses of every description, including stereoscope, 8urgical instrument, lantern lenses. magnifying mirrors, etc. Write for estimates and samples. We make 35 different styles and si.-:es of PHOTOGRAPHIC SHUTTERS and our factory is especially equipped to manufacture fine small metal articles of all kinds. furnishing the dies if desired. Estimates on application. Wollensak Optical Co., 292 Central Ave.. Roester, N. Y. THE UNDERWOOD STANDARD TYPEWRITER PLACED WITHIN YOUR GRASP TAKES CARE OF EVERY CLASS °F W°RK bY MODERN BUSINE5SJ IANDONTHEOS fMANY FEATURES THAT WARRANT INVESTIGATION UNDERWOOD TYPEWRITER COMPANY NEW YORK OR ANYWHERE BANKING BY MAIL NAVY AND.ARMY MEN We number among our depositors many of your associates in all parts of the world and invite you to send for full information, telling the manner in which they allot their salary to this large, safe bank, no matter where they are located. 4 PER CENT INTEREST Compounded twice a year, paid 00 aoy amouot Ask for wklet “ S-A,” explaining our system of Banking by M ail. THE CITIZENS' SAVINGS&TRUST COMPANY CLEVELAND. 0 The Oldest and Largest Trust Co., in Ohio. Capital and Surplus Million Dollars. class, and every member of it is hurt and indignant. Appeal in any particular case to the better feeling of a class, and the entire class will respond as one man. Class customs are handed down to posterity. To-day peculiar sentiments exist that were in vogue over twenty years ago, to the writer's knowledge, and undoubtedly long before that. Relaxation takes the form of outdoor sports and athletics of all kinds. There are track meets of running and jumping, throwing the hammer and vaulting. Baseball, football, tennis, basket ball, and other contests occur. The midshipmen have their glee club, and most years during the winter give a minstrel show and musical performance, to which officers and their families are invited. It is an exacting, but withal a joyous, interesting life. On an average, but fifty to sixty per cent of those who enter are graduated. The rest, failing in some way to give satisfaction, are dropped in the different years as the class progresses. The sentiment is that a midshipman must be a gentleman in all that the word implies. This is the obligatory standard of life that exists among these young men. The training in all respects is entirely controlled by naval officers. As these officers are constantly fresh from sea service, it means that the Naval Academy preparation reflects the ideas of the naval service at large. SIMPLE EXPLANATION OF MODEL BASIN METHODS. (Continued from page 420.) the model of a submerged strut, for example, might be negligible, while eddying around the full-sized strut of the actual ship would be serious. In the first case, the law of comparison would apply for practicable speeds. In the second place, it would not apply except as a rough approximation. As, however, eddy resistance is not a large proportion of the residuary resistance, and as the law of comparison applies fully to a portion of the eddy resistance and with fair approximation to the remainder, we are warranted in relying fully upon the law of comparison as regards residuary resistance. It is probably more reliable in the determination of the residuary resistance of a full-sized ship than the methods we must use for estimating its frictional resistance. It is in connection with propellers that the law of comparison becomes an unsafe guide. It is easy to make experiments with model propellers in a model basin and to apply the law of comparison to the results for the purpose of determining the thrust and power of full-sized propellers. This method has given good results in some cases and in other cases has failed, and the law of comparison has been sometimes discredited on this account. As a matter of fact, the fault is not with the law of comparison, but with the wrong use of it. A 12-inch model propeller 'with its center, say, one foot below the surface is working under a head of about 33 feet due to the atmosphere and one foot due to its submergence, or 34 feet in all. A 12-foot propeller submerged correspondingly 12 feet below the surface is working under a head of 33 feet due to the atmosphere plus 12 feet due to submergence, or 45 feet in all. The head under which it should work to correspond accurately with the model propeller would be 12 x 34, or 408 feet. The law of comparison should not be applied unless the conditions are such that it is applicable. It happens, however, that for moderate thrusts and speeds the motions around the model propeller and the full-sized propeller, in spite of the fact that they do not work under the proper relative heads, are essentially similar, and the ultimate reactions being due not to the pressures but to the motion given the water, the law of comparison does reasonably apply. When, however, the full-sized propeller Model A—$500 STAR RUNABOUTS 3 Models—$500, $600, $700 The nobbiest little cars on the market. Beauty, Simplicity, Ample Power, Perfect Control, and Low Cost of Maintenance make them the Ideal Car for business, professional or pleasure uses. Flexibly built to withstand hard usage on rough roads in city or country. Have three-point spring suspension, pneumatic tires, shaft drive and many other good points. Let us tell you about them. Fine selling proposition for agents. Good territory still open.' Special bodies for business purposes. STAR AUTOMOBILE CO., 303 Dearborn St., Chicago Classified Advertisements Advertising in this column is 50 cents a line. No less than four nor more than ten lines accepted. Count seven words to the line. All orders must he accompanied by a remittance. Further information sent on request. BUSINESS OPPORTUNITIES. LOCAL REPRESENTATIVE WANTED.-A large income assured to anyone who will act as our repre- e mail. Experience unnecessary.All we requireis non- tsty, ambition and willingness to learn a lucrative business. No soliciting or traveling. An exceptional opportunity for those desii' and make more money portunity for those desiring to better their conditions and make more money For full p:riculars OTite nearest office for free book No. National Cper- MOTION PICTURES. MOTION PICTURE MACHINES, Film Views, Magic Lanterns. Slides and similar wonders for sale. Catalo gue free. We also buy Magic Picture Machines, Films, Slides, etc. Harback&Co., 809 Filbert St., Phi la.. Pa. THE MOVING PICTURE WORLD, weekly, 10 cents per copy; yearly subscription, $2. The only paper devoted to the moving picture, illustrated song and lantern lecture field. Moving Picture World, Box 450, N.Y, WANTED.-Addresses of enterprising men contemplating entering the moving picture business. Biggest paying propositionforsmall capital knoOT. Writefor information. The Actograph Co ., 50 Union Square. N.Y. ity i o., MardenBuilding, Washington, D, C.. Phelps Building, Scranton, Pa. FRANCE. - Do you want to do business with France 1 I am contractor to the principal European Railway Companies, and have an Important connection among the great constructors, engineers, mines, and automobile makers. 1 can introduce a suitable speciality. Have you one? No antiquities required. Would undertake agency of first-class high-speed macbine tools for heavy cuts. Onlysoand Arms treats with. Establish 10 years in Paris. Best referencesgiven and required. Address Machinist, care of The Galignanl Library. 224. Rue de Rivoli. Paris (France). WANTED.--Good article to mauufacture and seU on royalty, or sales agency for same; have facilities: best references. “P'' 500, New England Building, Cleveland, Ohio. DOMINOCARDS, Great composite game set; domino shape with card colors. Play (cards, dominoes and new games “ Show-me” and “ Big-stick.” Parents fascinated, children deligbied; unique Xmas present; 56 parts in attractive box postpaid flOc. Order to-day. Domino- cards Co., l!!O Chouteau, St. Louis, Mo. QUICK SALES IS MY MOTTO.-U. 8. Pat. 864.257. May 21, 1907. Electric Heater, also patented 10-cent kitcben specialty. $l,000eac'i: F.Tob)er,1787 Hayes Street, San Francisco, Cal. GENTLEM A N desirous of getting Into the Automobile business can make a very profitable investment of o competent. Automobile Sales Corporation, 1661'Broad- way, New York. ARE YOU a young man . interested in electrical research? So am I. If you dispose of time and money for experiments drop me a line. E'er f:J'her information and full particulars address Inventor, P. O. Box IS, Brooklyn, New York. INVENTORS.-Send for free sample copy” World's Progress.” devoted to interests of inventors. All latest developments in scientific and industrial world. World's Progress, 510 12th St.. Washin#;on,D.C. AGENTS WANTED In every county to sell the Trans- parent Handle Pocket Knife Good commission paid. rom $75 to per month can be made. Writefor terms. Novelty Cutlery Co., No. 2 Bar St., Canton, O. PATENTED KEROSENE INCANDESCENT BURNER. 70 candle power; used on any lamp; saves 00 per cent, kerosene. Ready seller everewhere. Exclusive territory. Write forpartlculars. F.C.tottschalk, 265 Broadway. New York, PATTERN LEPTERS AND FIGURES (White Metal and Brass) for use on patterns for castings. Large variety. prompt shipments. Send for catalog. H. W. Knight&Son, Seneca Falls, N.d. THOUSANDS IN USE througbout the world. '15.00 “ Gem” Adding Machine, very compact, elegant side line. Special offer to bigh grade agents. Automatic Adding Machine Co., Dept. 4. 332 Broadway, New York. START A NEWSPAPER IN SOME LIVE TOWN. Good money in it for a hustler. Cost $5.OO weekly. I will tell you how to do it. G. Tunison, 15 Vandewater Street. New York. BOOKS AND MAGAZINES. ELECTRICIAN AND MECHANIC-Practical monthly magazine for electrical and mechanical students and workers. Publishes illustrated directions for conggi re telegrapn y, electroplating. elecirlcal wiring, mechanical drawing. using tools, furniture construction, boat building. all kinds of mechanical work. One doUar yearly; trial subscription for three months, twenty cents. List of electrical and mechanical books free. S. A.Sampson Pub.Co.,6Beacon st,Boston,Mass. INSTRUCTION UH and nlght,every late ma::' of car to work on-rti- culars mailed. Automobile Sales Corporation, 1661 Broadway, New York. PHOTOGRAPHY. AMERICAN PHOTOGRAPHY succeeds American Amateur Photographer, Camera and Dark Room and Photo Beacon. The editors of each now join In making a magazine which should be In the hands of every pho- toltl"apher, professional or amateur. 15 cents monthly, $1.50 jper year. Three specimen copies for a quarter. Am. Photographic Pub. Co., !:ll Broadway,New York. TALKING MACHINE NEEDLES. am Petmecky Multi-toneNeedles to all Interested In talk- eli ns sold weekly. Petmey, 3.1) Bro.rJway.New York. PATENTS FOR SALE. FOR SALE. American patent rights on Reinforcing Bar for concrete construction. Patent No. 857,671. For full particulars address A. V. Reyburn, Jr, 13 Uortense Place, St. Louis, Mo. FOR SALE. ENGINEER'S TACHYMETER FOR SALE. One Buff&Berger combined engineer's transit and level. In line condition, has been used about tbree weeks. In- bd l en tops. Price$m W. E.Koch, Whitefiall,N. Y. HELP WANTED. The fotl_ing positions are open in o.. new Gas Engine Works: SALES MANAGER to look after the wants of. and obtaining agencies. An offire man of large calibre, pleasing personality, fine correspondent, one who can obtain and hold large agencies. Salary $1.80 to $2,400 par year. also Interest in a highly profitable business after worth is demonstrated. Witte Iron Works Company, Kan8as City, Mo. re space, to operate two handred hands. Want notless than two thousand enlf\nes per annum, 8 to 40 H. P. at lowest possible cost, factory equipment the very best and latest. Must be an organizer of men, and a sys- terulzer of large experience. Salary $1.80 to $2,40 per year, and interest in business also. Witte Iron Works Company, Kansas City, Mo. CHIEF CLERK, experienced in checking In and outgoing invoices. doine some buying and repair order man. Salary $85 to $100 per month. Witte Iron Works Company, Kansas City Mo. STOCK CLERK, a competent inspector ot work en. tering stock room, who can pass on its grade, properly re h ex ence expected. Salary $100 per month. Witte Iron Works Company, K wsas City. Mo. DRAFTSMEN WANTED.-Looking for opportuni- o e e Twelve offices. Write to-day. stating experience. Hap- goods. Broadway. New York. ROYALTY SALESMAN WANTED to travel and El ace manufacture and sale on roy dty of splendid house- old article. Rlgbtman can clear $lf.1min a few months. Address XX, Box 773, New York. TYPEWRITERS. START MAKING MONEY by buying a reliable rebuilt typewriter. Remingtons, $15; Hammonds, Caligrapbs, Williams, Blickensderfers, Franklins, $10 up. Rentals, repairs. “Atlantic” Typewriter Ex., Dept. S, 245 B'way, N.Y TYPEWRITERS.-Hammond, $10; Remington, $12, Smith Premier, $18: Oliver, $29. All l1Uaranteed tor one year. Send for catalogue. Harlem Typewriter Exchange. Dept. B. 217 West 125th Street, New York. AUTOS. WANTED.-l.1m CHAUFFEURS AND REPAIR MEN . Our demand for professional automobile engineers ex. ceeds the supply; calls for men of intelligence and me. nm gr:3uation. Resident courses$15 to $50 Home correspondence courses in construction and repair , completed by practical road and shop work at auy of our branches or affiliated schools, highly successful. Look this up Auto Schools of America, 1680 Michigan Avenue, Cbicago. WANTED.—To hear from every individual autoiBt in the States and Canada, requesting our catalogue oi specialties and supplies, we make mud splashers, slip covers, top boots, chain boots, spark plugs, tires and tread covers, everything for the auto. Big discounts orders exceeding $5.00. Jenkins Specialty Mfg. Co., Sumter, S C. is worked at high pressures and speeds, the water is unable to follow the propeller, the motions cease to be similar, cavitation sets in forward of the full- sized propeller, and, of course, the law of comparison does not apply. The thrust and power of the full-sized propeller are very much less after cavi- tation is set up than would be inferred from model experiments by using the law of comparison. Parsons, with a proper understanding of the necessary conditions, has made some investigations of cavitation by testing model propellers in water nearly at the boiling point, so that the pressures around them are properly reduced. He found that a model propeller, which would not cavitate in cold water, would promptly show cavitation when the pressure was properly reduced by heating the water. In this case, as in many other cases, in applying model basin results to practice, it is necessary to understand the underlying conditions and circumstances before the methods are applicable. From model basin experiments we are able to determine more accurately than by any other known method at present the effective horse-power required to pull a ship through the water. But what we need to estimate in practice is the indicated horse-power required to be shown by the propelling machinery in order to drive the ship. The conditions are somewhat complicated. Of the indicated horse-power shown in the cylinders of a reciprocating engine, a varying proportion is absorbed in friction of the machinery itself, the remainder being delivered to the propeller. The propeller utilizes a certain proportion of the power which reaches it, the remainder being wasted. Furthermore, the propeller is not working in undisturbed water, but in the wake which is dragged after the ship and' which, acting on the propeller, virtually helps to push the ship ahead, thereby gaining power. But, again, the propeller by its suction tends to suck the ship astern, thereby increasing its resistance. It is on account of these numerous varying factors that we need to estab- 1ish an average ratio or a utilization coefficient, which is commonly called the efficiency of propulsion and is the ratio between the effective horse-power necessary to pull the ship at a given speed and the indicated horse-power necessary to propel it at the same speed. This ratio can only be satisfactorily established by comparison between numerous trial results of actual ships and model basin results, a fact which renders it of great importance to have accurate trials of full- sized ships whose model results are known. The efficiency of propulsion is commonly assumed at about 50 per cent for American Homes and Gardens HISTORIC MANSIONS of THE JAMES RIVER p HIS series deals with three of the most beautiful colonial estates along the charming and historic James River. The illustrations are made from photographs taken especially for the purpose by an expert. The series is of unusual interest and beauty. Subscriptions can begin with the September number. Price $3.00 per year. The three numbers will be sent on publication on receipt of 75 cents. Among the interesting articles in the October number are: SEPTEMBER, I907 I."Brandon,” the Home of the Harrisons. OCTOBER, 1907 II."Shirley,"' the Home of the Carters. NOVEMBER, 1907 III."Westover,” the Ances tral Home of the Byrds. EVELYN BYRD NINETEENTH CENTVRY BEDROOMS HOW TO TOVR IN AN AVTOMOBILE GARDENING WITHOUT SOIL SMALL AMERICAN HOMES PORT SVNLIGHT MILLBROOK FARM All these articles are beautifully illustrated. 72 large pages, colored cover changing each month. MUNN 6. COMPANY. Publishers Scientific American Office: 361 Broadway, New York City