July 6, 1888.] 



SCIENCE. 



— M. Wolf announced at the meeting in the French Academy, 

 June II, that Captain Dfforges had discovered in the arcliives of 

 the Ecole des Fonts et Chaussees a number of notes l:)y Prony 

 which show him to have been the discoverer of the modern meth- 

 ods of determining the force of gravity. In 1792 Prony proposed to 

 substitute for the simple pendulum a rod oscillating successively on 

 three parallel knife-edges. Later, in iSoo, the study of his first 

 apparatus led him to a contrivance which was nothing less than 

 the reversion-pendulum proposed in 181 1 by Bohnenberger, and 

 applied for the first time by Captain Kater in 181 7. Unfortunately 

 the many professional occupations of Prony and his journeys did 

 not permit him to make such a pendulum, and the memoir of 1800 

 was never published. 



— An exhibition of hygiene opens at the Palace of Industry in 

 Paris on the 20th of July. Another exhibition for the same pur- 

 pose, also containing a section devoted to the fine arts and the in- 

 dustrial arts, opened at Ostend on the 30th of June. 



— A recent number of the San Francisco Bulletin contains some 

 facts as to the exhibition under the auspices of the California State 

 Board of Silk Culture. " The exhibition is of a highly practical 

 nature, and comprises, in addition to reels, filatures, and cocoons, 

 over fifty thousand worms in different phases of development, 

 a great number of which, however, have reached the spinning- 

 stage, and are industriously engaged in the evolving of their 

 costly product. The manager of the work, Mrs. Louise Rienzi, is 

 an enthusiast in regard to sericulture, and is to be largely credited 

 for the rapid progress made by the board during the two years it 

 has been established. The impetus given to sericulture in Califor- 

 nia by the labors of the board has pushed the industry forward 

 vastly. Large invoices of cocoons are daily received, besides con- 

 siderable quantities of raw silk sent to be spun on the improved 

 filature machinery imported from Italy for this purpose. Appro- 

 priately enough, the majority of those who have engaged in silk- 

 culture in the State are ladies. Communications are received every 

 day from those desirous of obtaining information necessary to the 

 establishing of silk-farms. Besides being furnished with a book of 

 instruction, all who apply may obtain eggs or worms in embryo, as 

 well as mulberry leaves, trees, and cuttings. Fully sixteen thou- 

 sand trees and cuttings were distributed last spring as food-sup- 

 plies for the worms on sdk-farms located at Dutch Flat, Paso 

 Robles, Brentwood, Antioch, Howell Mountain, Sebastopol, Visalia, 

 Santa Paula, Templeton, Chico, Rutherford, San Jose, Irvington, 

 Danville, Anderson, Los Angeles, Eureka, San Bernardino, Fresno, 

 Livermore, Bowlder Creek, and numerous other towns throughout 

 the State. The leaves of one three-year-old tree are estimated to 

 be sufficient for the nourishment of an entire colony of silkworms, 

 while one hundred trees will supply the wants of as many worms 

 as can be attended to in any but the largest establishments. The 

 supply of trees and cuttings at the command of the board was ex- 

 hausted early in the present season, but the many applications held 

 over will be filled from the stock of fifty thousand trees which will 

 be procured for ne.xt season. 



— The Americati Meteorological Jojtrnal, desiring to direct the 

 attention of students to tornadoes, in hopes that valuable re- 

 sults may be obtained, offers the following prizes : for the 

 best original essay on tornadoes, or description of a tornado, two 

 hundred dollars will be given ; for the second best, fifty dollars ; 

 and among those worthy of special mention fifty dollars will be di- 

 vided. The essays must be sent to either of the editors. Professor 

 Harrington, Astronomical Observatory, Ann Arbor, Mich., or A. 

 Lawrence Rotch, Blue Hill Meteorological Observatory, Readville, 

 Mass., U.S.A., before the first day of July, 1889. They must be 

 signed by a noin de plume, and be accompanied by a sealed en- 

 velope addressed with same noDi de plume, and enclosing the real 

 name and address of the author. Three independent and capable 

 judges will be selected to award the prizes ; and the papers receiv- 

 ing them will be the property of the journal offering the prizes. A 

 circular giving fuller details can be obtained by application to Pro- 

 fessor Harrington. 



— At the meeting of the Engineers' Club of Philadelphia on June 

 16 it was voted that the club join in the invitation, which had been 



extended by other societies, to the International Congress of Geol- 

 ogists, to hold its fifth session, in 1891, in the city of Philadelphia. 



— In his article in a recent number of The Forum, Professor 

 Thurston takes occasion to remark that the world is awaiting the 

 appearance of three inventors greater than any who have gone be- 

 fore, and to whom it will accord honors and emoluments far ex- 

 ceeding all ever yet received by any of their predecessors. The 

 first is he who will show us how, by the combustion of fuel, di- 

 rectly to produce the electric current ; the second is the man who 

 will teach us to reproduce the beautiful light of the glow-worm 

 and the firefly, a light without heat, the production of which means 

 the utilization of energy without a waste still more serious than the 

 thermo-dynamic waste ; while the third is the inventor who is to 

 give us the first practically successful *air-ship. 



— • The Manhattan Chapter, New York, of the Agassiz Associa- 

 tion, held a silk exhibition at 103 Lexington Avenue, commen- 

 cing Friday evening, June 29, at 8 p..\[., with a lecture on silk 

 by C. F. Groth, and continuing Saturday, June 30, from 3 to lo 

 P.M.; Sunday, July I, from 3 to 10 P.M.; and Monday, July 2, from 

 3 to 10 P.M. 



— Prof. H. P. Bowditch has made an important contribution to 

 the growing literature of the ' knee-jerk ' phenomenon, the impor- 

 tance of which as an index of nervous condition is now so widely 

 recognized. Using an apparatus that allows the force of the blow 

 and the extent of the excursion to be recorded, he asks the subject 

 to firmly clinch the hand (and thus re-enforce the knee-jerk; upon a 

 given signal. After an interval varying from .1 of a second to 1.7 

 seconds, the blow is struck, and it is found that the effect of the re- 

 enforcement varies with the interval. It is greatest immediately after 

 the hand is clinched, and with an interval of .4 of a second has disap- 

 peared. With an interval of .4 of a second to i second, there is a dim- 

 inution of the knee-jerk, followed by an increase, reaching the nor- 

 mal again at 1.7 seconds. There is thus a short period of exaltation, 

 followed by a depression and a slow return to the normal. 



— A paragraph is going the rounds of the press, with what truth 

 we know not, to the effect that a company was recently started in 

 Philadelphia for the purpose of investigating the pyramids of Egypt 

 by boring into them with diamond drills, thereby penetrating into 

 some of the mysteries which have so successfully baffled the in- 

 vestigators of centuries. 



— The observations of M. Perrotin at Nice, and M. Terby at 

 Louvain, and, in England, of Mr. Denning at Bristol, have con- 

 firmed, according to Nature, the presence on the planet Mars of most 

 of the ' canals ' or narrow dark lines which were discovered by M. 

 Schiaparelli in 1S77, and at subsequent oppositions. M. Perrotin 

 has also been able to detect, in several cases, the gemination or 

 doubling of the canals, and M. Terby has observed the same phe- 

 nomenon in one or two cases, but with much greater difficulty than 

 in the opposition of 1SS1-S2. But some curious changes of appear- 

 ance have been noted. An entire district (Schiaparelli's Lvbiay 

 has been merged in the adjoining ' sea ; ' i.e., its color has changed 

 from the reddish hue of the Martial ' continents ' to the sombre lint 

 of the ' seas.' The district in question is larger than France. To 

 the north of this district a new canal has become visible, and again 

 another new canal has appeared to traverse the white north polar 

 cap, or, according to M. Terby, to divide the true polar cap from a 

 white spot of similar appearance a little to the south of it. With 

 the exception of these changes, the principal markings, both light 

 and dark, are those which former oppositions have rendered famil- 

 iar. 



— We learn from lYatiire that admirable arrangements have 

 been made for the London meeting of the International Geological 

 Congress, from Sept. 1 7 to 22 next. The meetings will be held In 

 the rooms of the University of London. Burlington Gardens, where 

 accommodation for the council, committees, exhibition, etc., has 

 been granted by the senate of the university. There is a refresh- 

 ment-room in the building, and there are several restaurants and 

 hotels in the immediate neighborhood. Arrangements will be 

 made at one of these restaurants for a room to be set apart for the 

 social meetings of members of the congress. The opening meet- 



