374 



SCIENCE. 



[N. S. Vol. XVI. No. 401. 



est dynamos ever made, viz., those for the 

 Manhattan Elevated Railway of New York 

 City. 



Electro-chemistry has not only made 

 aluminum a rival of copper as an electi'ic 

 conductor, but nearly all the copper is now 

 electrolytically refined. Calcium carbide, 

 from which acetylene is generated, is formed 

 under the electric arc; ordinary bleaching 

 powder is manufactured from common salt 

 by an electrolytic process; carborundum, 

 a new abrasive more effective than emery, 

 is made in the electric furnace, which as- 

 pires to the manufacture of graphite and 

 even diamonds. Electrically generated 

 ozone is used for the purification of water, 

 and a company has even been formed to 

 perfect a process for burning the nitrogen 

 in the air for the commercial production of 

 nitrates, which may go far to postpone the 

 impending wheat famine predicted by Sir 

 Wm. Crookes. 



Electric lighting represents an investment 

 of $669,000,000 in the United States. Great 

 improvements have lately been made in 

 electric lamps. These include the Nernst 

 lamp, which is a new form of incandescent 

 lamp ; the Bremer lamp, a new arc lamp ; 

 and the Cooper-Hewitt mercmy vapor 

 lamp, in which use is made of the incandes- 

 cence of a vapor or gas. The development 

 of new inventions, often very costly, is car- 

 ried on here in Pittsburgh as an adjunct to 

 regular manufacturing. 



Mechanical and engineering development 

 is a measure of a country's civilization, and 

 the United States possesses 69 per cent, of 

 all the electricity available in the world, 

 76 per cent, of all that portion available 

 for traction, 76^ per cent, of all the electric 

 railway mileage and 83-| per cent, of all the 

 trolley cars. 



The Genesis of Pittsburgh as a Seat of 

 Iron Manufacture: J. B. Johnston, of 

 the Pittsburgh Post. 



Some Consequences of the Trust Movement: 

 H. T. Newcomb, Editor of The Railway 

 World, Philadelphia. (Published in 

 The B.ailivay World of July 5, 1902.) 



The Statistics of the Dairy: Henry E. Al- 

 voRD, Chief of Dairy Division, U. S. De- 

 partment of Agriculture, Washington. 

 ( This paper will be printed in full in the 

 Proceedings of the Society for the Promo- 

 tion of Agricultural Science.) 

 The relative importance of this branch of 

 agricultural industry in the United States 

 is pointed out and the value of accurate 

 statistics thereof. The United States Cen- 

 sus is regarded as the principal source of 

 statistical information on this subject, but 

 is by no means the only one. The enumera- 

 tion of cows is the basis of reliable dairy 

 data, and this count by the twelfth census 

 is believed to be more complete and accurate 

 than any preceding. It included for the 

 first time the cows not on farms and ranges 

 — found to be 973,033 in niimber, or 5^ per 

 cent, of the entire milking stock of the 

 country. The whole number of dairy cows, 

 according to the census of 1900, was 18,112,- 

 707, and this is accepted as correct. Rea- 

 sons are given for believing the enumera- 

 tion of cows by the census of 1890 to be 

 entirely unreliable and hence all the dairy 

 statistics connected therewith. Conse- 

 quently, comparisons between the dairy 

 data of the eleventh census and the 

 twelfth are considered as entirely mislead- 

 ing and useless. 



Certain items in the dairy statistics of the 

 last U. S. census are pointed out to be miich 

 more reliable than others. The following 

 arrangement is presented as the probable 

 order of accuracy: (1) The number of 

 dairy cows, (2) the materials and products 

 of the condensed milk factories, (3) the 

 products of the cheese factories, (4) the 

 products of creameries, (5) the cheese made 

 on farms and sold therefrom, (6) the milk 



