22 REPORT— 1871. 



observations ; but tbe bore continues for aboiit 70 feet further. We have 

 here a total increase of 4° in 300 feet, which is at the rate of 1° in 75 feet ; 

 but the intermediate steps are so irregular that not much weight can be 

 attached to this determination. 



The Secretary has corresponded with the Smithsonian Institution respect- 

 ing the great bore at St. Louis, which was described in last year's Report, 

 and also respecting the Hoosac Tunnel which passes under a mountain and 

 will be 4| miles long, but the correspondence has not yet led to any definite 

 result. 



It was stated in last Report that application had been made to General 

 Helmersen, of the Mining College, St. Petersburg, for information regarding 

 the temperature of a very deep bore in course of sinking at Moscow, as well 

 as regarding underground temperatures in Russia generally. A long delay 

 occurred, owing to the General being absent from home for seven months, 

 and not receiving the communication till his return ; but shortly after his 

 return he dispatched a very polite answer, from which the following passages 

 are extracted: — " We have an artesian well in St. Petersburg, bored in the 

 Lower Silurian strata. At the depth of 656 English feet this well stops at the 

 granite, a granite which perfectly resembles that of Finland. The lowest 

 portion of these Silurian strata is merely a degraded granite, a grit combined 

 with debris of felspar. About 353,000 hectolitres of water flow from the 

 well per diem, and this water issues with a constant temperature of 9°-8 



Reaumur You are doubtless aware of the existence of a series 



of observations on the temperature of the soil at the bottom of a well which 

 was sunk in the town of Yakoutsk in Eastern Siberia. This well has shown 

 us that the soil of Siberia, at least in this part of its great extent, is frozen 

 to a depth of 540 English feet. The mean temperature of Yakoutsk is 

 — 8°-2 R. At the depth of 100 feet the temperature of the soil was found to 

 be — 5°-2. Prom this depth to the bottom the temperature increased at the 

 rate of 1° R. for every 117 feet; whence it would follow that the soil at 

 Yakoutsk is frozen to the depth of about 700 feet. 



" It appears to me a very interesting circumstance that, according to ac- 

 counts just received by the Icademy of Sciences from Baron Maydel, traveller 

 in the country of the Tchukchees [des Tschouktschi], there are found in 

 those regions layers of ice, quite pure, alternating with sand and clay. The 

 interesting letter of the Baron will shortly be printed in the publications of 

 the Academy. It was in making excavations in search of mammoths that 

 Maydel made this discovery." 



If we assume the temperature of the surface of the soil at St. Petersburg 

 to be 39°- 17 F., which, according to ' Herschel's Meteorology,' is the mean 

 temperature of the air at the Magnetic and Meteorological Observatory, and 

 if we take the temperature of the water as that of the bottom of the well, 

 we have an increase downwards of 14°-88 F. in 656 feet, which is at the rate 

 of 1° F. in 44-1 feet. If, on the other hand, we suppose the surface of the 

 ground to be 4° F. warmer than the air (and the difference at Yakoutsk ap- 

 pears to be greater than this), we deduce an increase at the rate of 1° F. in 

 60 feet. 



The rate of increase at Yakoutsk from the depth of 100 feet to the bottom 

 of the frozen well at 540 feet is given above by General Helmersen as 1° R, 

 in 117 feet. This is 1° F. in 52 feet. 



An account of the Yakoutsk well is given in ' Comptes Rendus,' tome vi. 

 1838, p. 501, in an extract from a letter by Erman (fils), who visited Ya- 

 koutsk when the well had attained a depth of 50 feet. He gives the tem- 



