■'^ s 0. Becker — Gravity Determinations at Sea. 



Art. XLII. — Remarks on tfo Paper by L. A. Bauer: " On 

 Gravity Determinations at Sea", by O. Hkckkr. 



Ix the above mentioned paper. L. A. Bauer is chiefly occupied 

 in criticising my gravity determinations at sea'. The stress of 

 work connected with entering upon my new office as director 

 of the Kaiserliche Hanptstation fur Erdbebenforschung at 

 Strasbourg in E. has prevented me from sooner taking notice 

 of L. A. Bauer's criticism, which, as will be seen in the course 

 of the present discussion, can only be considered as carelessly 

 made and mistaken in every way. 



The opening pages of the paper I need not discuss, as they 

 contain things which are generally known. I will only men- 

 tion that, as regards the experiments made on the " Carnegie" 

 with the boiling thermometer, an inferior way of reading the 

 thermometer is used, the thermometers being read with a hand- 

 lens, and not with a telescope, as done by me. There is no 

 doubt that in using a band-lens parallactic errors can easily 

 arise in the reading. Moreover, I wish to remark that the 

 barometer was read by eve. In a heavy sea the pumping of 

 the barometer was not less than 5 mm . Bauer says then : "sev- 

 eral settings were made, and both the low and high readings 

 were recorded". How this is possible, I cannot understand. 

 On the ocean, the period of the pumping of the barometers is 

 about 6—7 seconds ; hence, within 3 seconds the barometer 

 must be set and the vernier read ; for the positions which 

 follow each other must be recorded. For me it was quite im- 

 possible, even when the pumping was veiy small, to do this 

 with sufficient accuracy. 



I now come to Bauer's formula (5). He writes : "Hecker's 

 final observation equation is of the following form : 



/3f A\ + a ^j~ + bp + cr + ds + e(t— t o ) + k,=0" 



He gives the explanation of the meaning of the different 

 terms and of l\ he says : " A* 2 = constant which enters into the 

 equation only for deep-sea observations, say for depths begin- 

 ning with about 2000 meters." 



I am sorry to say, that Bauer must have gone through my work 

 in a very superficial way, or he would not have stated that my 

 observations were adjusted according to that formula. In the 

 first place, during the two cruises on the Atlantic, the terms cr 

 and ds were not used. Secondly, on the Indian Ocean, l\ has 

 quite a different meaning from that on the Atlantic: it is the 



*This Journal, vol. xxxi, pp. 1-18, January, 1911. 



