October 24, 1890.] 



SCIENCE. 



231 



tlie operations in which they are engaged, that they are 

 altogether unlikely to consider questions of utility; nor, in- 

 deed, is it desirable that they should. The evolution of pro- 

 cesses and methods by means of which the complex existence 

 of the present day is maintained is largely the result of spe- 

 cialiaation or the division of labor. In such a scheme there 

 is room for those who never demand more of a fact than 

 that it be a fact, of truth that it be truth. But even 

 among scientific men the number of such is small, and as a 

 class they can never be very closely in touch with the peo- 

 ple. 



Strong to imitate, even in those characteristics which are 

 akin to weakness, many persons of lesser note afl'ect a con- 

 tempt for the useful and the practical which does not tend 

 to eaalt the scientific man in the opinion of the public. Even 

 the great leaders in science have been misrepresented in this 

 matter. Because they wisely determined in many instances 

 to leave to others the task of developing the practical appli- 

 cations of their discoveries, it has often been represented 

 that they held such applications as unworthy a true man of 

 science. As illustrating the injustice of such an opinion, 

 ■one may cite the case of the most brilliant philosopher of his 

 time, Michael Faraday, who, in the matter of his connection 

 with the Trinity House alone, gave many of the best years of 

 hi& life to the service of his fellowmen. The intensely 

 "practical" nature of this service is shown by the fact that 

 it included the ventilation of lighthouses, the arrangement 

 of their lightning-conductors, reports upon various proposi- 

 tions regarding lights, the examination of their optical ap- 

 paratus, and testing samples of cotton, oils, and paints. A 

 precisely similar illustration is to be found in the life of our 

 own great physicist, Joseph Henry, who sacrificed a career 

 as a scientific man, already of exceptional brilliancy, yet 

 pi'omisiug a future of still greater splendor, for a life of un- 

 selfish usefulness to science and to his countrymen as secre- 

 tary of the Smithsonian Institution, as a member of the 

 Lighthouse Board, and in other capacities for which he was 

 especially fitted by nature as well as by his scientific train- 

 ing. 



There is an unfortunate, and perhaps a growing, tendency 

 among scientific men to despise the useful and the practical 

 in science; and it finds expression in the by no means un- 

 common feeling of offended dignity when an innocent lay- 

 man asks what is the use of some new discovery. 



[Continued on p. 232.] 



NOTES AND NEWS. 



^N important experiment has been "made in the province of 

 the Don Cossacks, Russia, by M. Sherebzov. He collected the 

 water from rain and the melting of the snows into two pools, 

 holding together about 1,873,000,000 cubic feet, and distributed it 

 among the fields in spring and summer. These pools supplied 

 sufficient water to irrigate more than 2,290 acres, but were unable 

 to contain all the water which flowed towards them ; and there- 

 fore two new pools have been made, and the irrigated area en- 

 larged to 2,960 acres. In consequence of this irrigation, says The 

 Scottish Geographical Magazine, the wheat-crop has increased 

 from about 9| to 15+ bushels per acre; and the profits of the un- 

 dertaking have been, according to M. Sherebzov, 30 per cent. 



— Nothing in the wonderful history of photographic progress, 

 which has been so strikingly rapid during the past few years, has 

 been of greater importance than the development of what may be 

 called, for want of a better term, " the photo-mechanical pro- 



cesses," which are so largely superseding wood engraving, steel 

 engraving, and other pictorial methods. This subject is of great 

 interest to the whole public, but particularly to all persons in any 

 way interested in the production or use of pictorial illustrations: 

 such as artists; authors; publishers of books, magazines, and news- 

 papers; printers; and manufacturers whose products require illus- 

 tration. For the past few years these processes have multiplied 

 in number, have improved greatly in their results, and are every 

 day assuming greater importance in both artistic and economical 

 directions; yet it is a remarkable fact that in no exhibition have 

 they been brought together for comparison and study. Beginning 

 Nov. 3, 1890, the New York Camera Club will give an exhibition 

 in its rooms, 314 Fifth Avenue, of the work of the various estab- 

 lishments producing all classes of such plates. 



— Attention was drawn some months ago by EngineeHng to the 

 very interesting experiments of Messrs. Mach and Salcber, who 

 succeeded in photographing bullets in their flight. These experi- 

 ments have been repeated with larger weapons, and the results 

 previously obtained fully confirmed. To obtain a photograph, 

 the camera is arranged at one side of the line of fire; and, as the 

 shot passes a fixed point, it causes the discharge of a Leyden jar, 

 the light from which is sufficient to allow of a photograph being 

 taken. No results of any importance are obtained, according to 

 Engineering of Oct. 3, till the velocity of the shot exceeds that of 

 sound. But at higher speeds than this the photographs show that 

 a wave of compression precedes the birllet in its flight. The shape 

 of this wave is an hyperboloid of revolution with the apex of the 

 hyperbola some httle distance in front of the shell. Behind the 

 shot a conical wave is formed, the angle of which is less, the 

 greater the velocity of the shot. If the semi-vertical angle of this 

 cone is o, the velocity of the shot is said to be 



velocity of sound in air 



sin a 



— The greatest enemy to the plum is the insect commonly 

 known as the plum curculio. This is the cause of the wormy 

 fruit that so often falls from the trees. Various remedies have 

 been tried for this pest, and for several years trials have been 

 made at the Ohio Experiment Station of the method of killing the 

 insects by spraying with a very dilute mixture of Paris-green and 

 water. The experiments were again repeated this season by the 

 station entomologist. Dr. C. M. Weed, with good results. An or- 

 chard of 900 bearing trees in Ottawa County, O., right in the 

 heart of a great fruit growing I'egion, was selected for the experi- 

 ment. In the north half of it the method of catching the curcu- 

 lios by jarring on a sort of inverted umbrella mounted on wheels 

 was employed, while the south half was sjirayed four times with 

 pure Paris-green mixed with water, in the proportion of four 

 ounces to fifty gallons of water. The first application was made 

 May 8, just after the blossoms had fallen from the late-blooming 

 varieties. There w as a heavy rain the same night, and it rained 

 almost continuously until May 15, when there was a short cessa- 

 tion. The second spraying was done on that day. The third 

 spraying was made May 26 ; and the fourth and last, June 2. On 

 the jarred portion of the orchard a great many curculios were 

 caught, showing that they were present in numbers. A careful 

 examination of both parts of the orchard was made on June 3. 

 Between one and two per cent of the fruit on the sprayed trees 

 had been stung, while about three per cent of the plums on the 

 jarred trees were injured. No damage to the trees was then per- 

 ceptible. Early in July the orchard was again examined. Some 

 of the sprayed trees showed that the foliage had been damaged by 

 the spraying, but the injury was not very serious. Not over three 

 per cent of sprayed fruit was stung at that time, while about four 

 per cent of that on the jarred trees was injured. But on both 

 the fruit was so thick that artificial thinning was necessary to 

 prevent overbearing. A large crop of fruit was ripened on both 

 parts of the orchard, and, so far as could be judged from the ex- 

 periment, the practicability of preventing the injuries of the 

 plum curculio by spraying was demonstrated. This process is 

 very much less laborious and costly than jarring; and, if future 

 experience is as successful as this season's work, plum-growing 

 will become much easier. 



