Intelligence and Miscellaneous Articles. 79 



feet, to take an additional rock-temperature and to then publish 

 in full the details of our observations. 



In the meantime it may be interesting to give the results as 

 the j stand. The highest rock-temperature obtained at the depth 

 of 4580 feet was only 79° F., the rock-temperature at the depth 

 of 105 feet was 59° F. Taking that as the depth unaffected by 

 local temperature variations, we have a column of 4475 feet of 

 rock with a difference of temperature of 20° F., or an average 

 increase of 1° F. for 223'7 feet. This is very different from any 

 recorded observations ; Lord Kelvin, if I am not mistaken, giving 

 as the increase for 1° F., fifty-one (51) feet, while the observations 

 based on the temperature-observations of the St. Grothard Tunnel 

 gave for an increase of 1° F., sixty (60) feet. The ca 1 dilations 

 based upon the latter observations gave an approximate thickness 

 of the crust of the earth, in one case of about 20 miles, the other 

 of 26. Taking our observations, the crust would be over 80 miles 

 and the thickness of the crust at the critical temperature of water 

 would be over 31 miles, instead of about 7 and 8*5 miles as by 

 the other and older ratios. With the ratio observed here, the 

 temperature at a depth of 19 miles would only be about 470°, a 

 very different temperature from that obtained by the older ratios 

 of over 2000° F. 



The holes in which we placed slow-registering Negretti and 

 Zambra thermometers were drilled, slightly inclined upward, to a 

 depth of ten feet from the face of the rock and plugged with wood 

 and clay. In these holes the thermometers were left from one 

 to three months. The average annual temperature of the air is 

 48° F. ; the temperature of the air in the bottom of the shaft was 

 72° F. — American Journal of Science^ December 1895. 



ON THE INFLUENCE OF ELECTEICAL WAVES ON THE GALVANIC 

 RESISTANCE OF METALLIC CONDUCTORS. BY H. HAGA. 



At the meeting of the Berlin Physical Society on Nov. 30, 1894, 

 M. E. Aschkinass* communicated observations according to which 

 the resistance of a grating of tinfoil was found to be about two per 

 cent, less in consequence of electrical radiation; and this small 

 resistance lasted even after the cessation of radiation, until heating 

 or mechanical agitation restored the former value. 



Since radiation will produce electrical vibrations in a tinfoil 

 resistance, it appeared worth while to investigate whether in 

 general the resistance of a metallic conductor is also altered by 

 electrical vibrations passing over its surface. 



Using the apparatus described and recommended by Ebertf, by 

 which long continuous electrical vibrations could be obtained, such 

 vibrations were transmitted through different specimens of copper 



* Verhandl. der Phys. Gesellschaft zu Berlin, vol. xiii. p. 103. 

 t Wied. Ann. vol. lii. p. 144 (1894). 



