ON UNDERGROUND TEMPERATURE. 67 



August 1893. In May 1893 the operations were suspended for the 

 purpose of making changes in the machinery ; and it was during this 

 interruption, which lasted three months, that the observations were 

 taken. The bore had attained a depth of 2,002 meti-es, exceeding by 

 255 metres that of the Schladebach bore, which was previously the 

 deepest in the world. When boring was resumed after the interruption, 

 and had added about a meti'e to the depth above mentioned, the boring 

 tool broke, owing to caving in, which proved to be of so serious a character 

 as to render further progress hopeless. The total depth attained is given 

 as 2,003-34 metres. 



The first 200 metres bored through consisted mainly of a greenish 

 grey clay or marl (Tegel), which was liable to swell and crumble after a 

 time if exposed to water. It also held the tubing with a grip which was 

 inconveniently tight. At about 250 metres a seam of coal was passed 

 through ; and in all eighty-three coal seams were found, with a total 

 thickness of about 90 metres. No mention is made of any springs being 

 tapped, but 14 metres of quicksand were passed through at the depth of 

 200 metres, immediately above the Coal-measures. The seams of coal 

 alternated with beds of sandstone and shale. 



The lower half of the bore, from 1,014 metres downwards, was not 

 tubed, but the upper half contained eight different sizes of tubing. The 

 first and largest extended from the top to 70 metres. Inside of this was 

 the second, reaching from the top to 107 metres. Within this was the 

 third, reaching from the top to 189 metres, and it was during the sinking 

 of the third that the diamond borer was substituted for the percussive 

 drill. The fourth size extended from the top to 260 metres ; the fifth 

 from the top to 319 metres ; the sixth from the top to 571 metres; the 

 seventh from the top to 1,014 metres ; and the eighth from 540 metres 

 to 1,014 metres, the necessity for this eighth tube having arisen from 

 accidental injury to the seventh. An accident which subsequently 

 occurred broke away a large portion of the eighth tube also, and as 

 repair was found to be impossible, a considerable length of the bore (from 

 the depth 571 metres to the depth 754 metres) was left without tubing, 

 constituting a standing source of danger and trouble. 



In place of the solid rods employed for supporting and working the 

 old percussive drills, hollow rods are employed in diamond boring, and 

 water forced down the interior of the hollow rods washes up the debris 

 through the surrounding space. The hollow rods are usually of wrought 

 iron, and this was the case at Paruschowitz till the depth of 1,450 metres 

 was reached, when, in order to diminish the enormous weight, it was 

 decided to replace the wrought iron by Mannesmann steel tubes ; a change 

 which was attended with great advantage during the remainder of the 

 boring. 



As regards the diameter of the bore, the tubing which lined the first 450 

 metres had an internal diameter of 92 millimetres. From this depth to 571 

 metres the diameter was 72 millimetres. Then occurred an untubed interval 

 of 183 meti'es of considerably larger diameter, the tubing of 72 millimetres 

 diameter commencing again at 754 metres, and continuing to 1,014 metres, 

 from which depth to the bottom at 2,002 metres thei-e was an untubed 

 portion of uniform diameter which had been bored with a diamond crown 

 of 69 millimetres. 



The method of plugging to prevent convection currents, which 

 was employed at Sperenberg and Schladebach, was not repeated at 



p2 



