396 



POPULAR SCIENCE MONTHLY. 



with the Nubian buck. The hitter ani- 

 mal is rather awkward in form and 

 movement, but M. Crepin hopes to breed 

 that out. Otherwise the Nubian is well 

 acclimated, vigorous, and indifferent to 

 cold, hornless, and a most excellent 

 milker. Goat's milk generally is richer 

 in cascine than cow's milk, and owes 

 some of its special qualities to this fact, 

 and to the further circumstance that 

 the flecks of goat-milk cheese are small- 

 ei', softer, and more easily broken up 

 — consequently more digestible — than 

 those of cow's milk. Further, goat's 

 milk is more nearly than any other 

 common milk like in composition to 

 human mother's milk; and it has the 

 very great advantage that, the goat 

 being less subject to attacks of tuber- 

 culosis and other dangerous disorders, it 

 is comparatively free from the liability 

 to convey infection. A single objection 

 to the general use of goat's milk is the 

 odor which is supposed to be character- 

 istic of it, but M. Cr6pin affirms that 

 this is not apparent when the goats are 

 properly bred and kept. M. Cr6pin is 

 experimenting with butter from goat's 

 milk, and represents that he finds it 

 very nice. 



The fundamental principle involved 

 in the new form of telemeter, or instru- 

 ment for estimating the distance of 

 visible objects without actual measure- 

 ment, invented by Herr Zeiss, of Jena, 

 is that of the stereoscopic eflfect which 

 appears in natural vision, where the in- 

 clination of the eyes in concentrating 

 on the object gives the sense of dis- 

 tance. The base line between the eyes 

 is increased in the Zeiss instrument by 

 means of a system of prisms so as to 

 give a widened base of binocular vision, 

 and of mirrors which give magnifying 

 power. Double images are formed, the 

 distance between which varies in pro- 

 portion to the distance from the ob- 

 server, and appliances are provided for 

 measuring how far apart they are. The 

 arrangement is fairly satisfactory for 

 moderate distances — say of 3,000 me- 

 tres, or about 10,000 feet. 



M. MoissAN believes that he has 

 found a solution of the problem of the 

 manufacture of ammonia from the at 

 mosphere, and consequently of render- 

 ing atmospheric nitrogen available in 

 agriculture, by the artificial production 



of calcium nitride. While calcium un- 

 dergoes no change in contact with ni- 

 trogen at the ordinary temperature, it 

 is affected by it under the operation of 

 heat, and finally burns in it, absorbing 

 it rapidlj' and giving rise to a bronze- 

 colored nitride. Thrown into water, 

 this substance decomposes with effer- 

 vescence, producing ammonia and cal- 

 cium hydrate. 



Prof. A. E. Dolbear, of Tufts Col- 

 lege, Massachusetts, patented an inven- 

 tion for telegraphing without wires in 

 1SS6, which he claims covers all that 

 Marconi is doing. He has sent mes- 

 sages with it for as long distances as 

 five miles. According to his account he 

 invented the system and made success- 

 ful experiments with it as far back as 

 1882. He made an application for a 

 patent, which was rejected by the Pat- 

 ent Office with the statement that it 

 was contrary to science and would not 

 work. " But as it did work, the claim 

 was maintained in the office, and four 

 years later, in 1886, a patent for it was 

 issued." Professor Dolbear does not 

 wish it to be understood that his patent 

 is on tlie " art of wireless telegraphy," 

 Init that it covers everything that has 

 been so far done in the art. 



On the occasion of the visit of the 

 French Association to the British Asso- 

 ciation, Prof. J. J. Thomson gave an ex- 

 position of the lines of research by 

 which it has been concluded that the 

 atom is not the smallest existing quan- 

 tity of matter. Electro-chemical phe- 

 nomena teach us to associate a definite 

 amount of electricity with each atom 

 of matter; but these recent researches 

 indicate that under certain circum- 

 stances a much larger quantity of nega- 

 tive electricity may be conveyed by the 

 atom, or else that the negative elec- 

 trical charge resides on a small detach- 

 able portion of the " atom," which alone 

 is concerned in the experiments. The 

 positive charge seems to be distributed 

 over the whole mass of the atom. 



The merits of two methods of clari- 

 fying sewage — by dilution and by bac- 

 terial action — are discussed by Mr. Ru- 

 lolph Hering in articles in the Engi- 

 neering Magazine. Disposal by dilution 

 in large streams of water is regarded as 

 satisfactory in many places — where the 

 water of the stream is not to be used 



