160 REPORT — 1875. 



feeder of water was met with at 790 feet on penetrating the Lower Keuper 

 Sandstone, and another at 950 feet in the Bunter Sandstone, the water 

 from the latter rising above the surface. The bore-hole is being lined 

 with tubes. 



The best observations were taken on the 15th, 16th, and 17th of June, 

 1875, the hole having remained undisturbed since May 27th. These obser- 

 vations were as follows : — 



Temperature. 



Date. Depth. Fahr. Time down. 



feet. o h m 



June 15 100 68 10 



„ 200 68^ 30 



300 68| 30 



400 68| 30 



500 68| 30 



„ 600 69 30 



700 69 30 



„ 800 69 30 



9°° 69 30 



June 16 looo 69!^ 35 



ii°° 69! ' 35 



„ 1200 69^ 30 



1303 yoi 35 



June 17 1400 71 35 



1500 73 40 



At an earlier date. May 13th, the hole having been undisturbed for a few 

 days, the temperature 68|° was found at 1308 feet, which was the depth 

 then attained, and the temperatures GG°, 66°, 66°-2, 66°-G were found at the 

 respective depths of 0, 300, 490, 590 feet. The instrument employed on 

 both occasions was the protected Negretti maximum thermometer. 



These observations illustrate the difficulty of obtaining correct results in 

 the presence of strong springs of water. It is obvious that nearly all the 

 above temperatures are largely affected by convection. If we assume the 

 temperature at the bottom in each case to have been free from this source of 

 error, as well as from disturbance by the heat generated in boring (assump- 

 tions which are somewhat doubtful), and if we estimate the surface- tempe- 

 rature at 49°, we have the following mean rates of increase : — 



Between feet and 1308 feet 1° T. for 68 feet. 



„ 1308 „ 1500 „ 1 „ 40 



„ 1500 „ 1 „ 62-5 





A bore-hole is being sunk to a depth of 2000 feet at Bohmisch-Brod, near 

 Prague ; and the Secretary has received two independent applications for 

 thermometers for the purpose of making observations in it — one of them from 

 the Academy of Sciences of Yienna, the other fi'om the Imperial Polytechnic 

 School at Prague. Two thermometers (one of the Negretti and one of the 

 Phillips pattern) were supplied in each case, the expense being defrayed by 

 the recipients. These applications are gratifying, as tokens of an increasing 

 interest in the subject of underground temperature. 



Two protected Negretti thermometers have been sent to Dr. Oldham, 

 Director of the Geological Survey of India, to be used in borings for coal in 

 that country. Arrangements are also being made by Mr. Blanford, Director 

 of Meteorological Observations for India, to establish regular observations of 

 earth-temperature at small depths at certain selected stations. 



