50 



SCIENCE. 



[X. S. Vol. XXI. Xo. .524. 



are accurate enough for the purpose for 

 which they were compiled, that is, to show 

 the rehitively small area covered. There 

 is, however, another side to the picture, the 

 hopeful one. In South America the arc 

 of Peru is being remeasured and extended 

 by the French government. As the work 

 is being carried out with the advice of 

 the most distinguished mathematicians of 

 France, the results will be, in their impor- 

 tance, out of all proportion to the extent 

 and area involved. 



]\Iexico has made a brave beginning and 

 is working towards a connection with an 

 extension of the ninety-eighth meridian 

 measurement, of which the United States 

 has completed about three quarters of the 

 amplitude lying in her own domains. Work 

 on the Pacific coast arc has been resumed 

 and it has nearly been completed from San 

 Diego to the Columbia River. 



Two years ago the Russians and Swedes 

 jointly completed an arc in Spitzbergen 

 between latitudes 76° and 81°. The Euro- 

 pean arcs are being extended eastward by 

 Russia, and one must look forward to the 

 ultimate connection between the Russian 

 triangi;lation at Astrakhan or Orsk and 

 the Indian triangulaticn, however improb- 

 able it may seem if looked at from a po- 

 litical view point. 



In Africa the work of extending the 

 South African arcs northward from the 

 Cape towards Alexandria is well under 

 way, and no doubt need be entertained that 

 the British and Germans will carry it 

 through. 



A general review of this part of the 

 field of geodesy shows that while some 

 great geodetic measurements have been 

 completed or are approaching completion, 

 new ones are being undertaken imder the 

 fostering care of different governments. 



Reasoning from the experience of Iho 

 past, we may c(mclude that the solution of 

 one problem in geodesy will disclose the 



existence cf another, and from the trend 

 of the investigations cf the present that 

 other than purely mathematical and astro- 

 nomical sciences will be advanced by the 

 search for their solution. 



That the progress of the branches of 

 science to which this section of our asso- 

 ciation devotes itself was greatly affected 

 by the problems of geodesy was pointed 

 oxit by Humboldt in language which may 

 fittingly conclude these remarks: 



E.xeept the investigations concerning the par- 

 alhix of the fixed stars, which led to the discovery 

 of aberration and nutation, the history of science 

 presents no problem in which the object obtained — 

 the knowledge of the mean compression of the 

 earth and the certainty that its figure is not a 

 regular one — is so far surpassed in importance 

 by the incidental gain which, in the course of 

 long and arduous pursuit, has accrued in the gen- 

 eral cultivation and advancement of mathematical 

 and astronomical knowledge. 



O. II. TiTTMANX. 



U. S. Coast .\M) Geodetic Survey. 



FUTURE DEVELOPMENTii IX PHYSICAL 

 CHEMISTRY.'' 



It has been the custom of the retiring 

 officers to discuss the development of some 

 portion of that field of chemistry in which 

 they were most interested. Since the 

 president of the American Chemical So- 

 ciety will speak on physical chemistry to- 

 morrow night, it has seemed to me that I 

 might break with tradition and discuss the 

 future of physical chemistry rather than 

 its present or its past. 



We have reached a critical stage in the 

 development of the electrolytic dissociation 

 theory. The work of Kahlenberg has 

 shown that there are a number of facts 

 which we did not anticipate and which we 

 can not explain satisfactorily at the pres- 

 ent time. The recent experiments of Noyes 

 show that the dilution law does not hold 

 foi- any strong electrolyte and that the 



* Address of the vice-president and chnirman of 

 Section C— Chemistry, Philadelphia, 1004. 



