TWELVE MILES INTO THE EARTH

Dominion, Volume 13, Issue 148, 18 March 1920, Page 7

TWELVE MILES INTO THE EARTH

! SIR CHARLES PARSONS'S SCnEJIE. ■ Sir Charles Parsons, lecturing at the Royal Institution, referred to his ])roi posal for sinking a bore hole. 12 miles 1 deep into the earth. He said that the cost of boring the hole would not be 60 .very great. : ! Thp deepest single-stage shaft on the. \ Rand is the Hercules, -loOOft. deep vertically and rectangular in section. The' deepest shaft in the world is the Morro A T elho in Brazil: its bottom is (MflOft. • vertically below the surface, and it has i [ Iteen sunk, and is worked, in.stages, two ' , of which are about. 1200 ft, vertical, '''hei deepest shaft designed on the Rand is ' . one" of the City Deep Company's 7tVWft. i vertically, of circular section, 20ft. in ,' . diameter, and to be worked in two j stages of 3500 ft, each. In countries where the atmosphere is i dry .the sides of the shaft are cooled by' i sprinkling them with water, tho evapora-- j tion of which cooled the rock. This 1 . I efi'ect might be augmented by artificially' ; drying and cooling the air before passing ' it down the mine. With etill greater j depths of 6hnft further niethods of cool-' j ing would probablv be necessary. Tho> ! . heat might be carried upwards by meahs j | of brino circulated in a closed ring of I steel pipes with a rising and descending ' column, or a Bimpler method would be.' I to arranee for a rain of liquid air down ! the shaft. When sinking the deeper, i portions of the shaft, probably shields j - would he required to protect the miners i • from the splintering of the rock, since. I > the intense compressive stress splits off | scales from tho surface, sometimes with } considerable violence. | When Sir Charles Parsons first brought i forward his suggestion in,l9>Lth_e esti-, 1 mnte of the time required to sink a' *j shaft 12 miles <l<>en was 80 years; but; | with, improved machinery and the records have been so ; much lowered j that lie now thinks an estimate of 30' j • years reasonable. At the Crown Mines, ; 310 ft. of .a. circular shaft, ,20ft., in diameter, wcr<> sunk in a month. i