January 16, 1885. 



SCIENCE 



47 



Lord Rayleigh has been engaged upon a 

 study of the silver voltameter and its applica- 

 tion to the measurement of electrical currents. 

 He finds that one ampere deposits four grams 

 of silver per hour, and a sufficient amount 

 can therefore be obtained for accurate weigh- 

 ing in fifteen minutes. Pure nitrate or chlo- 

 rate of silver gives the best results. Beetz 

 has proposed a new form of Daniell cell, of 

 great internal resistance. Fine alabaster plaster- 

 of-Paris is mixed with concentrated sulphate - 

 of-copper solution, and the copper electrode 

 is fixed in this at one end of a glass tube : 

 the rest of the tube is filled with concentrated 

 sulphate of zinc and plaster-of-Paris, and the 

 zinc electrode is also embedded in this. The 

 ends of the tube are filled with paraffine. This 

 form of cell has been tried at the Jefferson 

 physical laboratoiy of Harvard univershVy, and 

 has been found an excellent substitute for the 

 water-cell of zinc and copper for charging 

 electrometers. 



The lull in the progress of theoretical elec- 

 tricity is probably the precursor of important 

 additions to our knowledge ; for many investi- 

 gators are at work, both at home and abroad, 

 testing the new electrodynamic theory of light, 

 and adding to our knowledge of magnetism. 

 The equipment of prrysical laboratories in Amer- 

 ica, which has been one of the features of the 

 y^ar at Cambridge as well as elsewhere in 

 America, bids us hope for much s} r stematic 

 stucly of the science of electricity, and physi- 

 cal science in general. John Trowbridge. 



CO-ORDINATION OF THE SCIENTIFIC 

 BUREAUS OF THE GOVERNMENT. 1 



The land-maps of European countries are, as a rule, 

 made under the direction of the war departments of 

 those countries, and under the direction of officers of 

 the army specially detailed for that duty, with the aid 

 of experts in the business and in the arts necessary 

 to the surveys and to the production of the charts, 

 who are employed from civil life, and also of enlisted 

 soldiers and non-commissioned officers detailed from 

 the army. 



For details on this subject, the committee refers to 

 the printed notes on European surveys compiled and 

 published in 1876, under the direction of one of its 

 members, Gen. C. B. Comstock, U. S. engineers, as 

 the most complete compendium on this subject known 

 to them; also to some manuscript notes prepared by 

 the committee from reports and publications of later 

 date. 



1 Extracts from the report of a committee of the National 

 academy of sciences, consisting of Gen. Meigs, and Professors 

 J. P. Trowbridge, Pickering, Young, Walker,' and Lang- 

 ley. 



The hydrographic surveys of the coasts of Europe 

 appear in every country to be the work of the naval 

 establishment. On the coasts of the United King- 

 dom the hydrography has been completed; and now 

 two parties in surveying vessels of the navy are con- 

 stantly employed in re-sounding and examining chan- 

 nels, harbors, and shoals, iri order to correct the 

 existing admiralty charts. All this is done under 

 direction of the admiralty. 



While the organization of the land and of the hy- 

 drographic surveys in Europe are very perfect, your 

 committee does not find that they offer any thing to 

 improve that of the United States, except, perhaps, in 

 showing the economy in time and money of greater 

 use of photography and of zincography in the reduc- 

 tion and production of maps and charts. In Great 

 Britain now the twenty-five-inch-to-the-mile map is 

 published even earlier than those on smaller scales, 

 all of which are reductions from the original manu- 

 script maps surveyed and plotted on the twenty-five- 

 inch or six-inch scale. 



Early and cheap publications of results of opera- 

 tions in the field, if they retain the accuracy of the 

 original maps, are of great industrial and economic 

 importance. The English maps of the ordnance 

 survey are published and placed on sale as soon as 

 printed, and at very moderate prices. 



Your committee would call attention, in this con- 

 nection, to the report made by the National academy 

 of sciences to congress in December, 1878, in which 

 the advantages of a consolidation of the then exist- 

 ing surveys were pointed out. In that report, it was 

 recommended that surveys should be two in number, 

 — the coast and interior survey, to be concerned with 

 the triangulation and mapping of the country and 

 its topography ; and a geological survey, to undertake 

 geological and economical investigations. It would 

 be a part of the duty of the former survey to supply 

 the maps for the use of the geological survey; and, in 

 order to secure the co-ordination and harmonious co- 

 operation of the two surveys, it was recommended 

 that the coast and interior survey be transferred to 

 the interior department. 



Congress adopted so much of this recommendation 

 as related to the formation of a single geological sur- 

 vey, but did not provide for the proposed transfer of 

 the coast-survey, nor make any other provision for 

 the topographic work necessary for the geological 

 survey. The result has been that these two surveys 

 do not co-operate as they should. The chief of the 

 geological survey has also found it necessary to em- 

 ploy large corps of men in trigonometric measure- 

 ments. 



Your committee does not feel entire confidence 

 that the union of these two surveys under either one 

 of the executive departments, would, without other 

 measures, necessarily lead to that unity of work 

 which is desirable. It therefore recommends certain 

 further legislative measures, the occasion for which 

 will be made clear by a review of the work done by 

 these several organizations; but its members are 

 entirely clear in the opinion that some one of the ex- 

 ecutive departments should control both. It is for 



