76 REPORT — 1895. 



The first experiment was a failure, the thermometers, though left for 

 about an hour near the bottom of the bore, indicating about the same 

 temperature that they had before lowering. This failure is attributed 

 either to the non-conducting action of a few thicknesses of soft paper in 

 which the bulbs were wrapped, or to the mercury which had left the bulbs 

 having returned to them again while the tube was being conveyed from 

 the bore to the plumber's shop, where the cap-piece was removed. 



In the second experiment ' no paper was wrapped round the bulbs, 

 but the brass dust was continuous from the bulbs to the sides of the iron 

 pipe.' At the depth of 2,733 ft. an obstruction was encountered which 

 prevented the tube from going lower, and which also caused the suspend- 

 ing wire to kink and break. After an immersion of about twenty-seven 

 hours, the wire was successfully grappled, and the tube brought to the sur- 

 face. ' The upper cap-piece was then rapidly heated in a chafing dish of 

 charcoal made of an old nail-can, with a hole cut out of the bottom just 

 sufficiently large to admit of the upper eixd of the tube being passed up 

 it, and oxygen gas from a compressed cylinder was blown through a 

 Fletcher's blowpipe on to the charcoal, so that in less than half a minute 

 the solder in the threads of the cap-piece was melted ; the lower portion 

 of the tube containing the thei'mometers being meanwhile wrapped in wet 

 cloths to prevent the heat travelling downwards. The cap-piece having 

 been unscrewed and the thermometers withdrawn, the highest temperature 

 registered was found to be 97° F.' ' Not a drop of water had found its 

 way into the tube.' 



On the following day the experiment was repeated, no wire being used 

 for lowering, but only tarred rope ; and sheet lead was wrapped round 

 the tube to increase the weight. The tube was left down for one hour, 

 and the maximum temperature registered was 96° F. The difference of 

 1° below the former observation is what might fairly be expected from 

 the stirring of the water and the thermal capacity of the sheet lead 

 which, with the tube, weighed 30 lb. The first result, 97° F., is therefore 

 adopted as the true temperature at the depth of 2,733 ft. The mean sur- 

 face temperature, as determined by Mr. H. C. Russell, is 63° F., giving 

 an increase of 34° in 2,733 ft., which is at the rate of 1° F. for 80 ft. 



As regards the possibility of disturbance of temperature by convection, 

 Professor David mentions in a letter to the Secretary that the bore was 

 only four inches in diameter. He also says, ' You understand, of course, 

 that we can do nothing in the way of taking temperatures in a diamond- 

 drill bore until the bore is quite completed, owing to the chilling of the 

 rock at the sides of the borehole by the cold water which is being con- 

 stantly forced to circulate under pressure through the bore.' 



The temperatuie of the water of Port Jackson at the greatest depths 

 near Cremorne, varying from 45 to 63 ft., was found (on December 6, 

 1893) to be uniform at 68° F. As this temperature is higher than that of 

 the ground at the same level, no cooling effect can be attributed to the 

 water. The slow rate of 1° F. per 80 ft., deduced from the observations, 

 would therefore appear to be a good approximation to the truth. 



It is expected that shafts will shortly be sunk at Ci-emorne, and will 

 afford opportunity for the systematic observation of rock temperatures 

 from the surface to a depth of nearly 3,000 ft. 'The first 1,000 ft. will 

 be in horizontally bedded sandstone, and the remainder chiefly in clay 

 shales, with interstratified sandstones and conglomerates.' The observa- 

 tions will be taken by Professor David and Mr. Pittman, with the 



