T/ie Editors are not responsible for the Opinions expressed tm their Cor respondents. Sxpandlng Steam—Test of Engines, MESSRS. EDITORS :—On page 197, of your current volume, I criticised the claims of certain steam engine builders by comparing their pretentions with some of the known laws of mechanics. These builders claimed, that in working steam at 60 pounds pressure in their engines, it expanded to 16 volumes,and still retained a pressure of 3 pounds, and showed diagrams of cards to prove the claim. I asserted that no such card could have been fairly taken from any engine, under the conditions claimed. From the editorial remarks upon that communication, it is evident that you understand me to have deduced those conditions from the diagram. This is not strange. But how your correspondent, on page 230, who claims to speak for those builders, and is, of course, familiar with their circular, sould honestly think that the figures I gave of the amount of steam admitted to the cylinder, were obtained by estimate from the card, is a little more wonderful. The truth is, I made no estimate whatever, of the amount of steam admitted, nor of the power obtained; but took both from the positive statements of the circular. It is there stated that steam enters the clyinder at 60 pounds, and follows only 1- inches, and is instantly cut off. Again, (I quote from the circular), thus we have the area of a 12-inch cylinder, which is 113 inches by 1—169-50 inches of steam to move the piston from one end of the cylinder to the other. And again, steam striking the piston at 60 pounds, and falling to the 3 pounds at the end of the stroke, gives us an average pressure of 17-J pounds, the entire length of the cylinder, requiring only 169 cubic inches of steam. It was the above conditions that I asserted could never be ealized by any engine. Tour Utica correspondent, forgetting these statements, very kindly informs us, that it is an error to suppose the amount of steam used is measured by that admitted to the cylinder up to the point of cut-off, that it is the volume of steam In the cylinder, at the opening of the exhaust valve, which determines the quantity of heat required to do the work. Could this important truth have been discovered by the parties who publish the circular in -question, before analyzing their own diagram, what a difference it would have made in their figures Their cylinder contains, at end of stroke, 3,712 cubic inches of steam, of 3 pounds pressure, by the gage. This, if admitted at 60 pounds, could not, with the smallest possible allowance for attenuation, have expanded to more than four volumes, so that, in place of using only 169 cubic inches, as they assert, we have, by this rule, at least 678 inches. Here is a slight difference in figures, but perhaps it may be of no consequence to yo.ur. (respondent, as he proposes to disregard some other matterlSf importance. He says, The item of units of heat lost in developing power may be disregarded, or rather only regarded generally along with other losses, of which the indicator takes no note, such as leakage of piston and exhaust valve, condensation, etc. , Now, it is true thai leakage of piston, and valves, and condensation, are not considered in the theory of expansion, but the assertion that, in practice, they are taken no note of by the indicator, will certainly be received with surprise. And as to the heat lost in developing power, either the theory that disregards it is false, and the indicator that fails to note it unreliable, or the whole doctrine of the correlation of forces is untrue; for, according to that doctrine, the heat lost must be the equivalent of all the power utilized by expansion. The writer complains that the card published in the SCIENTIFIC AMERICAN is not exactly a reduced copy of the one in the circular, that the compression curve is not made by lead of steam valve, and that the card shows a negative steam lead, etc. It is true this card is slightly inaccurate, but is rather nearer to the described card in the circular, than their own diagram. As to the compression curve and the negative steam lead, every engineer knows that by closing the exhaust valve early and compressing the steam remaining in the cylinder, the pressure will rise at the end of the stroke, independent of the opening of the steam port; but that this pressure will continue to rise, the steam valve not opening until the piston has moved some little distance on its forward stroke, is a discovery for which science must be greatly indebted to your Utica correspondent. Now, a word on the practical side of the question : Mr. J. H. Fountain, of Elmira, N. T., has, in his flouring mills, at that place, one of those short cut-off engines, which was warranted by the sanguine builder to save 40 per cent of fuel over any single slide valve engine. A test was was by the builder, of a ten hours run, which was satisfactory to himself, but not to Mr. F., who has since put in a smill slide valve engine. This he did for the purpose of making a careful test. Under date of April 4th, he writes me as follows : We tested the slide valve engine last week, on a ten hours run, with the same kind of grain and fuel as with the engine that was to save 40 per cent of fuel, and the slide valve ground more grain, and with less /Wthan the other, saving just twelve per cent from the amount used by the short cut-off. The small one, too, worked to great disadvantage, as it was set on light timbers, in a temporary manner geared to the shaft of the other, and with a long steam pipe to it. Mr.(the buiMer), on making a test personally, with his engine, pronounces t as good a result as he ever knew, yet it is badly beaten by this country made engine.. . . Mr. F. also says, that the short cut-off gives an irregular motion, jamming the machinery, loosening the irons in the stones, the toes of the spindles, etc., which might be expected as a natural result, where the initiatory pressure is high and the final pressure a partial vacuum, Keokuk, Iowa, E. S, WICKLIN, 311 Cheap Gas, MESSES. EDITORS :—In reply to the writer of the article Cheap Gas, page 295, current volume, of the SCIENTIFIC AMERICAN, who sgns P. W. K., and criticises some of the statements made by me in a previous communication. I simply wish to remark, that never having personally made the subject of transmission of gas through mains a speciality, I employed for my calculations formulae given by some of the best modern gas engineers, such as Clegg, Pole, dHarcourt, Hughes, etc., in their published works. I was fully aware that further experiments in this direction were much needed, and think that P. W. K. would supply a desideratum by favoring the SCIENTIFIC AMERICAN with the result of his studies on this important question. When, however, he affirms that he can carry carbureted hydrogen gas through mains a distance of 200 miles with a loss of less than 5 per cent by leakage, I cannot help expressing skepticism, since it is a well-known fact to all persons interested in gas works, that a larger amount of gas then that stated is actually wasted everyday in the best constructed mains, and this on a stretch of five or six miles only; not simply by leakage at the joinU, but by a remarkable phenomenon of direct penetration of the very substance of the pipes, analogous, if not identical, with dialysis, during which a certain portion of air is substituted for the escaped gas. What I attempted to prove, was that bringing gas from the coal regions to New York through mains, would not cheapen it to the consumer, and would not be conducive of profit to the producer. This, I again affirm, notwithstanding what P. W. E. may say to the contrary. Supposing the plan a feasible one under his management, and at his own figures of $32,000,000, we see that the very interest on this sum of money would amount annually to no less than $2,275-000, or very nearly the present amount paid for freight on coals, leaving but a very small margin for the eventualities of such a venturous enterprise, or on which to base a reduction in the price of gas. It would prove quite as profitable, and, I cannot help but believing, considerably safer, to place the goodly millions in a well-managed bank, and to continue, as heretofore, to pay freight on coal out of their accumulated interest. I am, personally, a firm believer in the theory of the necessity of the division of labor, and in the great principle of live and let live, whether it be applied to the builders of our railroads, to the makers of our gas, or to the illuminated masses in general, whose own fault it is, if, in this free country of ours, through the choice of their representatives, they are imposed upon by monopolies. Reduced freights, and a little more conscientiousness on the part of the gas companies, are all the consumer in this great metropolis calls for at present. When P. W. K. has successfully put his project into operation, I shall be the very first to cry out mea eulpa, especially if he thereby diminishes my present gas bill 50 per cent, as he promises to do, but uutji th,en, he must excuse me for dissenting from his views. X. Y. Z. [Our correspondent is right. We consider it entirely impracticable, at the present time, to manufacture gas at the mines and conduct it through pipes to distant cities.—EDS. Calculating Horse-power ot Engines, MESSES. EDITORS:—I notice an article under the above caption, on page 278, No. 18, current volume of the SCIENTIFIC AMERICAN, which is so manifestly crude and fallacious that, to prevent those who are not thoroughly posted on steam and steam engines from being misled, I offer you this note; not, however, that I expect thai your correspondent will be converted, for he is an old hand, and it is not expected that he will learn new tricks, especially as he is so unfortunate as to find a scientific engineer with such an unfortunate rule. Now let us look at a comparison of the two engines. The one 14 by 26 inches, 80 revolutions per minute, 3464 feet; the other, 8 by 12, 450 revolutions per minute, 900 feet. According to the old hands theory, they are, respectively, thus : the 8 by 12 is equal to 28-horse power, the 14 by 26 is 3333-horse power. Now, then, let us see what power they do absolutely exert to move themselves and the load or resistance attached. In making the calculation we will take the Old Hands own data, so far as the elements required are put down; viz., the diameter, stroke, revolutions per minute, and pressure of steam on the piston. Of course an old hand would give the pressure on the piston, right from his good opportunities for observation, though he dont believe in textbooks, or even the SCIENTIFIC AMERICAN Give him the power of the 8 by 12, with 56 lbs. pressure per square inch on the piston, the resistance overcome would be 7672-horse power. The 14 by 26 would be 89-26. Perhaps, before he writes another article on the subj ect, it might be well for him to ascertain what constitutes a horse power, as known and used by engineers. If he finds it to be a given weight raised through a given space in a given time, he then can very easily find what pressure is required to do it, and will thereby learn that it is simply weighing, and measuring—the alphabet of engineering. Now the discrepancy between the rule of thumb and the true rule, as above described, is a little too large for me to believe. Twenty years experience and good opportunities are unfortunately at conflict with Gunters rule and Pairbanks scale. ENGINEER. Tlie Dynamical Iiever. MESSES. EDITOHS :—It appears to me that some of your correspondents have given the dynamical lever credit for effects which it has no agency in producing. A correspondent in No. 18, current volume, page 277 of your j paper, conceives that the fact that a horse can move, on a wheeled vehicle, 2,500 lbs. at the rate of 176 feet per minute (equal to 440,000 lbs, one foot per minute), while the aver- i 1 age capacity or power of a horse is 33,000 foot-pounds, is due to some magical power of the dynamical lever. Now, a horse can move, in a canal boat, a great deal more than 2,500 lbs. at the rate of 176 feet per minute, without the , aid of wheels, or any other form of dynamical lever. How ) will your correspondent account for this ? His error consists in not recognizing the fact, that the moving of a ponderous body upon a horizontal line and on a vertical line are not precisely the same thing. Again, this correspondent thinks, that the fact that a horse can move a heavier load, at the same speed, on a cart with large wheels than with small ones is due to the mysterious virtues of the dynamical lever. In this he is mistaken. The fact is due to a difference of friction between the axle and the hub. To illustrate : Suppose you have a load of 2,000 lbs. on a cart. It is manifest that, at every revolution of the wheels, whether large or small, you will have-to overcome the friction due to 2,000 lbs. weight on the bearings of the axle in I the hub. If the cart has wheels 6 feet in circumference, to move it 60 feet you must overcome the friction of 10 revolutions; but if wheels, 12 feet in circumference, to move it 60 feet, you will only have to overcome the friction of 5 revolutions, j In other words, by doubling the circumference of the wheels,; you reduce the friction one-half. And this is the only reason why a horse can draw, on a level plain, a heavier load, at the same speed, on large wheels than on small ones. J. J. C. [With this letter we shut down on this dynamical lever discussion. Our first correspondent, P. R. P., has been so clearly in the wrong throughout the entire discussion that any further demonstration of his error is unnecessary. We therefore wish no further communications upon this subject. If any of our readers should see fit to criticise the views of J. J. C. in regard to the origin of the gain in the use of large wheels on draft vehicles, there is room for some profitable discussion on that point.—EDS. I&equired Power for Velocities, MESSRS. EDITORS :—In the SCIENTIFIC AMERICAN, of May 1, page 278, are several communications on the above subject. One from P. R. P., on his dynamical theory, to which it is hopeless and useless to reply. Wm. Horsnell overlooks the reduced load to the engine of one-half (so considered) when disconnected—thence, requiring only half pressure of steam for equal revolutions—but giving double with same amount of steam. A. Dean is laboring under a fundamental error in supposing a double velocity does not require a quadruple force. The pendulum exhibits this law very clearly. Its vibrations, whether of number or size, are dependent on the force (gravity) acting on the disk. A quadruple force is requisite to double the number, or to double their size respectively. The usual estimate of Vibrations by the square root of the length of the rod (inversely) is correct, but is merely incidental to the governing force of gravity, the weight sustaining action of the rod, taking off the gravitating force in the above ratio. Mr. Dean correctly states that in practice there is a loss not taken into account by the leading features of increasing velocities—the main loss would be in additional slip to the paddle or screw—inversely as the square root of the power applied, for the water, in conformity to the foregoing law, requiring a quadruple force to give way, or slip a double distance. Mr. Dean maintains that resistance is as the distance, without regard to time of making it; if it were so, a bluff-built vessel would be as easily propelled as one of sharp lines, for the midship sections is the measure of the water displaced in either case. Pittsburgh, Pa. Facts vs. Philosophy—Hot Air. MESSES. EDITORS:—In your issue of April 24, is a labored article on the Heating of Buildings. Much might be said to show its unsoundness, on its ow n basis, but I shall be content now with giving facts. Pornore than twenty-five years we have lived in a stone house warmed by a hot-air furnace. The house has been kept warm, or even hot, night and day. We have raised a family of eight children, four ot each sex. My wife is rather a feeble woman. Twenty-five years ago I weighed 145 lbs.; now weigh 225 lbs. Our doctors bill has not been one hundred dollars for the twenty-five years. We have had no death in the family, our children are all vigorous and healthy. More than half of them have left home and settled in different States in the Union. Our family have suffered less with colds, and other kindred complaints, than almost any other family. If this is destroying health and comfort please give us more of it. I know of many other families whose houses are heated by hot-air furnaces, who will testify to their great utility and comfort. Let doctors philosophize, the people are bound to live on. G. W. H. Lockport, N. Y [The logic of facts is hard to withstand, and if the cases cited by our correspondent were the only facts bearing upon this subject, we should have to admit that he had made out a fair case for the heaters. He has cited us a few cases where people have enjoyed good health and got fat, notwithstanding the heaters. We could cite many more where their deleterious effects were quite as obvious. His wife, he says, is in feeble health. Ha it ever occurred to our correspondent, considering the difference in peoples constitutions, and the other significant fact that she is more exposed to the injurious effects of the heated air, that possibly the heaters are the cause of her debility—EDS. J -— Taps Cutting Varying Threads, MESSES. EDITORS :—Is it a possible thing for a nut to be : cut with a tap of a given number of threads other than the treads on the tap ? i I have a tap that in the hands of an unskillful workman cut some three-quarter inch nuts in a manner that I cannot understand. The tap is a machine one that goes through the nut and leaves it on the shank. It cuts ten threads to the I inch. He cut some of them correctly, the tap going through the nut in about forty revolutions. Those that were cut wrong were cut in about ten revolutions of the tap, it making five entrances to the nut, instead ot one, as it should have done. W. H. K. [We have often been puzzled with the difficulty alluded to by our correspondent, but never with a machine tap. We never could account for it, nor understand the reason why. It is usually attributed either to defect in the tap or in the hole to be threaded, but this hypothesis is not sustained by the facts. An explanation from an observant mechanic would be well received.—EDS. Fall of a Smoke Stacls. MESSRS. EDITORS :—A short time ago the smoke stack, or chimney, of the flouring mill of Read & Bottom, of this place, fell, causing the entire destruction of the mill. The building was of brick, and the chimney fell across it, smashing walls, machinery, and everything before it. The cause of the fall appears to be the softening of the brick by the steam from the escape pipe, which had been turned into the chimney. The escape pipe was let into the chimney near its base, and at this point the brick could be crushed between the fingers, while the balance of the chimney was perfectly solid. As others may be allowing their exhaust to pass into their chimneys, it might be well to sound a note of warning. Pairfield, Iowa. Machinery not Mostfle to Mental Culture. The North British Review, in discussing the essays of Matthew Arnold, upon Culture and Anarchy, thus disposes of that gentlemans asseitions relative to the hostility of machinery to the highest culture of mankind. We cannot think that human nature, in finding an outlet for its many-sided activity in the direction of machinery, acts in a way that is hostile to culture. We prefer (as in the case of religion) to include the practical tendency which finds scope in new inventions to accelerate labor, and to supersede manual toil by mechanical contrivance, within the sphere of culture. Let it be admitted, that it is intrinsically of much lower value than any other kind of effort, bearing on the perfection of the individual. Still, as it implies the victory of man over Nature, insight into her laws, and the utilization of her processes, it is the condition of other and higher grades of culture; and inasmuch as it is a virtual necessity of human life, let us concede its value and respect its tendency. Diamond Tifrniiig Todl tor Vulcanlzetl Knl1)er aul Emery Wheels. We desire to call attention to the advertisement of the New York Belting and Packing Company, on the last page of this issue, of a new diamond-pointed turning tool for trueing- up vulcanized rubber and emery wheels. The trueing up of these wheels by heating their perimeters to soften them during the operation of turning, as has hitherto been the practice, was liable to leave their surfaces in a softened and friable condition, unless the heat was carefully regulated during the process. One of these new tools will turn up a wheel eight inches in diameter, and having a face one and one-fourth inches wide, from three to four hundred times, leaving the surface in the best condition for work. The turning can be quickly and easily done without heat or other aid to the action of the tool. The objections which have hitherto been made to the use of these wheels for certain kinds of work, seem completely obviated by this invention. -4. The L,aw of Steam. BY J. DEBT, O. E. Calling P the pressure of steam in atmospheres; A the latent heat in steam of atmospheric pressure (537 deg. C, equal to S666 deg. Pah.); L the latent heat in steam of any other given pressure, in atmospheres; 6 a constant number (which ior Cent, scale is 17, and for Pah. scale 306); T the Cent, temperature of steam, and T its Fah. temperature; V its relative volume to water, and S its specific gravity, we see that for every decrease in the latent heat of steam equal toll Cent units, or 306 Pah., there corresponds a doubling of the press-lire; a decrease in volume, equivalent to the number of times, minus one, that the number 17 is contained in this decrease of latent heat; an increase in weight equal to the number of times, minus one, that the number 17 is contained in the decrease of latent heat; an increase in specific gravity equal to 000059; and an increase in sensible heat, equal to 244 Cent, or 35-92 Pah. If P=l, thenL=537; T=100C.; V=1896; W=6232H-1696; S = lH-1696. If P =2, then L=537—17; T=100+244; V=1696H-2; W=62-32H-(1696H-2); S=1H-(1696H-2). If P=4, then L=537—(2 X 17); T=100 + (2x 24-4); V= 1696H-3; W=62-32-H1696H-3); S=lH-(1696-=-3). All the above are derived from a law, which we now announce as follows: The pressure of steam increases in a geometrical pro gression, the terms of which are multiples of two, as 1, 2, 4 8, 16, 32, etc., while the latent heat decreases in a compound arithmetical progression, the constant of which is 17 Cent, or 306 Pah., and the multipliers, respectively, as the numbers 0, 1, 2? 3, 4, 5, etc. 312 machine for Making Drain Tile. It is only a few years since draining lands by means of tiles was considered an experiment expensive in its operation and doubtful in its results. That period of doubt is past; and now tile draining is known to be a paying department of agriculture, not only for cultivated and arable lands, but for those which otherwise, from natural sourness, refuse to yield any return to the labors of the agriculturist. Any means, therefore, that facilitates the production and lessens the cost of drain tile is worthy of encouragement. The engraving shows a machine for making drain tile, consisting of a pug mill, having the usual curved knives, or arms, tor disintegrating the clay, a screw-follower for carrying and forcing the prepared clay into the dies, and a series of dies or formers to give size and shape to the tile. This screw follower and an assortment of dies are seen in the fore- , ground of the engraving. In front of the die-openings is a bench containing a set of rollers, the surfaces of which are hollowed to receive the pipes as they come from the formers, and the operator, by; means of a hinged frame furnished with cross wires, cuts the continuous pipe into proper lengths, while another attendant removes them to the kiln. The blades of the pug mill reduce the mass of clay to a plastic condition, and the lqwest series of blades are simply semicircular disks set spirally on the upright shaft, forcing the material on to the conveying horizontal shaft, furnished with a continuous spiral blade and a cone-shaped former turning within the fixed die. The continuous screw forces the doughy mass through the dies on to tha- rollers of the bench, where the fully-formed pipes are cut to convenient lengths by the hinged frame with its cutting wires. The rapidity of production of the machine is limited only by the alacrity of the attendants in taking away the sections (the mill being kept well supplied with material). Patented through the Scientific American Patent Agency Oct. 4,1859, and Feb. 26,1861. Orders for Eastern, Middle, nd Southern States should be addressed to Crossman Clay and Manufacturing Co., Woodbridge, N. 3. For Western territory, address H. Brewer & Son, Tecumseh, Mich. Improved Three-Wheeled Velocipede. Probably the greatest objection to the three-wheeled velocipede, as ordinarily constructed, isnot that it is larger than the bicycle or that it inquires a greater exercise of power to propel it,butthat everySnotion of the rear axle, whqi: either of its wheels passes over anobstacle, is conveyed dilectly to the seat and to the body of theJ%ler,Bo that there, ia a. ijaaatttjatcMng.tQ 3iigS%Mti: left, which is wearisome to the rider -andprevents that graceful motion that. constitutes half the charm of the exercise to the operator and attraction to the spectator. Another difficulty in the ordinary three-wheelers is inability, to turn short corners. The rigidity of the machine prevents any tipping or leaning of the body of the rider and the machine itself, that is as requisite in riding the velocipede in a circle or around a curve, as though the rider was mounted on a horse careering around the circus ring, or on skates cutting a figure eight. It is evident, therefore, if these objections can be removed and if the tricycle possess the ease of guiding and grace of action of the bicycle, it will, in many cases, where safety is preferred to daring, be chosen. The inventor of the improvement shown in the accompanying illustrations thinks he has succeeded in this object. The improvement consists in the manner of connecting the forward or driving wheel with the rear axle by means of the reach, which is a hollow pipe, combining strength and light-lightness, or of round iron. On the front this connecting bar or reach is curved to the cir-cumfeiettessf the forward wheel, then brought to a level, and running back to the center of the rear axle in direct line with the forward wheel and at the level of the axle. A sleeve, in which the reach turns, embraces it forward of the axle, to which it is secured by diagonal braces, as seen in Fig. 1. Directly over the rear axle, the end of the reach is secured to a cross bar, A, and a spring, B, Fig. 2, the ends of the latter resting on the axle. As the rider leans one way or the other, and the forward or guiding wheel is directed, the bar and spring are brought down to the axle, as seen plainly in the dotted lines of Fig. S. Thus the tipping or lifting motion of either forward or rear wheels is independent of each other. The bar prevents too great an action of the spring, while the rider is not compelled to exert his force or employ his weight to direct the rear wheels. In applying the power the ends of the fork that holds and guides the driving wheel extend below the axle, and a light steel frame is secured to studs prejecting from the lower ends of the fork and to the ends of a yoke forming part of the fork directly over the wheel. In this steel frame there is a slide on either side to which the crank is connected, and also the treadles. The steering bar is of the usual form, The action of the slides is aided and the friction reduced by rollers; the stirrup, or treadle is adjustable to the length of limb of the rider. The feet have simply a direct up and down motion, not describing a circle, thus enabling the vehicle to be driven more rapidly with the same amount of motion of the feet. The inventor says that as the rider has only one wheel—not the whole machine—to keep upright and receives considerable assistance from the spring, it is a much easier machine to ride than the bicycle; as short a turn can be made with it, a slower motion sustained, and less chance for accident, as it cannot be overturned, and it is suitable for children and inexperienced persons. Invented and patented by W. S. Hill, Manchester, N. H., through the Scientific American Patent Agency, April 18, 1869. The entire right is for sale. Address as above. Chair Wanted. The American Builder anxiously asks : Will somebody tell us where we can buy a chair ? Se waiit h office chair, a parlor chair, a dining-room ctsair, and a:kitofi.en chair. We have experimented in chairs for a number of years, and always with the same results. They prove the wickedness of men who, in these degenerate days, make things to sell. Now, if there is any thing in the world built for the use of an American citizen which should be built in a substantial manner, that thing is a chair. It should be so constructed as to sustain a weight of two hundred pounds avoirdupois, on four legs, two legs, or one leg. As these very necessary articles of furniture are now constructed, they will not stand alone any considerable length of time in a room heated to a comfortable degree of temperature. The worthless glue with which they are stuck together thaws out, and then they fall in pieces. Some years ago we purchased of a highly reputable dealer— among the most reputable of his class, we mean—what we considered a very substantial as well as high-priced set of. office chairs. They were in pieces in less than a month, and the reputable dealers tinker was called upon, week after week, to pay them his attentions. But the tinker, with his glue pot, failed; whereupon we called in a son of Vulcan, who substituted iron in the place of glue, and with astonishing success. Subsequently, having occasion to purchase a set of office chairs, we thought to profit by our former experience, and, remembering the splint-bottomed arm-chair of oar grandfather, which never broke down, we searched the city for duplicates. We found them after many hours search. Alas these too were like the others; they commenced coming to pieces within a fortnight. We have arrived at the conclusion that chairs put together with glue are worthless. Now, will not some inventor give us a chair ? We incline to the belief that a fortune is awaiting the man who will devise a method for putting together chairs in such a way that glue shall be dispensed with entirely. The Crows Valttk to the Farmer. Whatever wrongV crow commits against the cultivators of tHsoil may, by a little painstaking, be materially lessened or wholly prevented. The benefits he confers are both numerous and important. During the time he remains with us he destroys, so says no less anuthority than Wilson, myriads of wonfmoles, mice, caterpillars, grubs, and beetles. Audubon also.affirms that the crow devours myriads of gruBss every day of the year—giubs which fwotff lay waste the farmers fields—and destroys quadrupeds innu-merable, every onef wGich iaBf enemy to his poultry and ihisfflocks. EMaarris also, one of the most faithful andlM&uiate observers, in speaking ofJftlie fearfwravages sometimes wrought in Htr grasjpands and gardens by the gnrtof-tlieMambeetles, adds Ms testimony to the greatfeSRoes rendered by the crowin kefipingnhejSjpests in check. Tet herg,inMaslachisetts,ygltrdless of such tes-iinioiiyiin their favor, Jfre have nearly exter-mmalMjthesefMrdsfMld the destructive grubs, Mving-nolpnger thfc active enemy to restrict theirgpwti/fef jp,r lAyear increasing with a feajftltoersiltSiceSEFe have seen large fai.lhJnyanVhArl ride of Boston, in which , fiyerOTriHcrgfthe grass was so completely undermined andmefrepyeOTrfihtf ay, that the loosened turf could be rolled up,iasjHl&y1Sfcfiit had been cut by the turfing spade. In thejBnetefflk$rhood whole fields of corn, potatoes, and almdslfgiftimtof garden vegetable, had been eaten at the root; dl(gsMPbd. Our more intelligent farmers, who have dlBKdied out the cause of this unusual insect growth, le&sRfied themselves that it is the legitimate result; the matumPand inevitable eonse- quence, of our own acts Our shott-sighted and Brurderons warfare upon the crow has interrupted the harmonies of Nature, disturbed her well-adjusted.balance, and let loose upon agriculture its enemies withfadequate means of arrest. ing their general increase.—AtlaHttk) WmtMy. Recommencement nf ttaWrajfaScavaMons; at Hercu- All those who take an interest in antiquarian studies, says the Eclectic, will rejoice to hear that, after a century of almost total neglect, the excavations at Herculaneum are now to be resumed, King Victor Emmanuel having conceived, or at all events carried out, the happy idea of assigning for this purpose an annual grant of thirty thousand francs to the charge of his civil list. He has, furthermore, undertaken to provide for the maintenance of a pupil at the Archaeological School of Pompeii. These measures have been received with uncommon satisfaction in the Neapolitan provinces. As befitted an event of such importance as the recommencement o f the long-abandoned excavations at Herculaneum, the opening ceremony was directed, and the first clod loosened by the king himself. What a rich harvest of dis-covery may reward the toil of future laborers in this mysterious soil What further insight into the domestic life of the ancient world may not be obtained from the imprisoned treasures that have [at last obtained their orders of release The two buried sisters, Herculaneum and Pompeii, have undergone a very different fate in these latter times. The earliest researches were instituted in Herculaneum with magnificent results; but partly from the hardness of the material in which the ruins are imbedded, and partly also from a fear of endangering the foundations of the modern town of Portici, the works were discontinued and transferred to Pompeii, where the labor is far easier and, therefore, more remunerative. As a set-off against this defect, the works of art unearthed here are generally of a superior character, not only because Herculaneum was itself a seat of a richer and More refined community, but also because the difficulties attending the excavations at Herculaneum have preserved its contents from the depredations to which Pompeii has been subjected at various periods. WE understand that extensive preparations are making at Lowell, Mass., to test the powers of turbine wheels by an entirely new method, the test to take place about the middle of May. The precise day is not yet fixed.
This article was originally published with the title "Correspondence" in Scientific American 20, 20, 310-312 (May 1869)