:!','•_' 0. //<<■/>>/■ — Gravity Determinations at Sea. 



cruises, then' is also an agreement comparable to the mean 

 error of the observations. 



P>ut what does Bauer now do? He adds to my determina- 

 tions the topographic and isostatic corrections calculated by 

 Eayford, and in comparing the anomalies with those observed 

 in America or elsewhere, he finds, that to him they are too 

 large I need not waste words on such an unscientific method 

 of procedure. A valuation of the magnitude of the anomalies of 

 gravity, as one must expect them on gigantic Graben, such for 

 instance as the Tongadeep, where I observed a depth of over 

 8500 meters, is something which even geodesists have not 

 hitherto been able to arrive at. The topographic and isostatic 

 corrections can certainly be calculated, but not the anomaly. 

 I should, however, like to draw attention to a work of E. 

 Kohlschiitter,* well worth reading, and in which he speaks of 

 the determinations of gravity that I made in the Pacific. Based 

 on a study of the determinations that I made, Kohlschiitter 

 arrives at quite a different conclusion about the precision of 

 my observations, from that of Bauer. 



Bauer then speaks about the " Method to be tried on the 

 Carnegie," as if this method were quite a new one. This 

 method seems to be the same as the one I made use of, 

 except that he introduces the freezing-point observations; but, 

 although he has no experience in the matter, he thinks that by 

 means of an instrumental arrangement it may be possible to 

 render a series of corrections unnecessary. He writes : "It is 

 believed that equally good, if not indeed superior results can 

 be obtained with less equipment than used by Hecker." He 

 is welcome to his belief, although I am astonished at this 

 dictum. It would certainly have been better, if he had first 

 proved the reality of his opinion by results, instead of giving 

 only his opinions ; for, as far as I know, he has made no deter- 

 minations of gravity at sea until now. 



The reason why I made no freezing-point observations is 

 that they would have introduced new errors into the observa- 

 tions ; for freezing-point observations are also subject to 

 errors. 



Bauer intends to make such observations every week, or as 

 often as necessary, in order that he may immediately reduce ; 

 he forgets, however, the fact that even if he could deduce the 

 changes of the thermometers therefrom, he gains nothing for 

 estimating the constancy of the barometers, which play an 

 equal part with the boiling thermometer. At the end of his 

 paper he seems, however, to feel this. 



*Ueber den Ban der Erdkruste in Deutsch-Ostaf rika, Vorlauflge Mitteilung, 

 Nachrichten der k. Gesellschaft der Wissenschafteu zu Gottingen, Mathe- 

 matisch-physikalisehe Klasse, 1911. 



