36 EEPOBT — 1889. 



The above description applies especially to tlie taking of observations 

 at the bottom of the bore. When it was desired to isolate a column of 

 ■water at a considerable distance from the bottom, the apparatus employed 

 consisted of two portions. The above description applies to the upper 

 portion, and the lower portion was similar to it but inverted, resting upon 

 rods which extended to the bottom. The two masses of clay in this case 

 cut off a water-column between them. 



Experiments with a model, in which the bore was represented by a 

 cylindrical glass vessel 26 cm. high and 55 mm. wide, filled with water, 

 showed that the isolation was very good, and that it remained so though 

 the immersion lasted more than ten hours. In tearing away the clay 

 from the vessel a portion of the clay fell into the water, but such an 

 accident occurring in the bore would be of no consequence. 



The construction of the isolating appai'atus was entrusted to Bore- 

 Inspector Kobrich, under whose management the observations were to be 

 carried out. 



Besides the thermometer in the isolated wa'er-column, there was a»- 

 second maximum thermometer in the open wate." just above the upper- 

 plug, for comparison, the height of its bulb above that of the principal 

 thermometer being 2'8 m. 



The thermometers were very similar to those employed at Sperenberg, 

 They were overflow-thermometers, generally without scales, and were- 

 enclosed (for protection against pressure) in a hermetically sealed case of 

 stout glass with an external diameter of 15 mm. To take the reading, 

 the thermometer, after being drawn up, was put with a normal ther- 

 mometer into a vessel of water at a temperature a little below that which 

 was expected. Warm water was then gradually added, and the whole 

 kept stirred till the mercury in the overflow-thermometer reached the- 

 open end. The temperature at this moment was then read by the other 

 thermometer. 



In the annexed figure, ah is the thermometer, enclosed in the strong 

 glass tube c, to which it is not fastened. A quantity of loose 

 mercury, the surface of which is shown at x, is also contained in 

 this tube. Overfiow takes place at the end h, which is cut off 

 obliquely so that any mercury which issues from the tube will 

 run down the slope. To refill the thermometer, the instrument 

 is warmed till overflow commences, and is then promptly in- 

 verted. The thermometer thus slips down to the other end of 

 the case, and its open end, h, is immersed in the loose mercury, 

 some of which is drawn into the thermometer as it cools. 



The first observations taken were in the untubed portion of 

 the bore, which at that time extended from the depth of 1,240 m. 

 to 1,376 m. ; and as the bore was deepened to 1,748 m. the 

 observations were continued. In this way the last sixteen observa- 

 tions of Table I. were obtained, forming a series at intervab of 

 30 m. from 1,266 m. to 1,716 m. of depth. 



A pause which subsequently occurred in the sinking of the 



bore, through having to wait for a new tube, was utilised for 



taking the observations which form the remainder of the Table. We 



have thus a complete series of observations, at equal intervals of 30 m., 



from the depth of 6 m. to that of 1,716 m. 



The Table is arranged in five columns. The first column contains the 

 natural numbers from 1 to 58, for convenience of reference to the observa- 





