134 REPORT — 1873. 



It is called Brandon "Walls shaft, and belongs to the Eookhope Valley Mining 

 Company, to the courtesy of whose agent we are indebted for liberty to take 

 observations. This shaft is some G miles cast of those reported on last 

 year, and is situated in the very bottom- of llookhope Yalloy. - The mouth 

 is covered over with a wooden shed, the shaft itself is free from all obstruc- 

 tion, and the water in it has not been disturbed for some years. The shaft 

 is 333 feet deep, and is full of water to within 25 feet of the surface of the 

 ground. Observations (by ]Mr. Burns and Mr. Curry, of Bolkburn) were 

 taken in it on five diftererit days in July of the present year ; but though 

 agreeing well with one another from day to day, they are so irregular that 

 they throw little light on the rate of increase of underground temperature. 

 At the depths of 83 and 133 feet from the ground the temperature was 

 4S°-5. In the next 50 feet there was an increase of about 3°, the tempera- 

 ture at 183 feet being about 51°-4, and from this depth to the bottom (an 

 interval of 150 feet) the temperature was nearly constant. The best deter- 

 mination of the temperature at the bottom was 51°- 7. 



It may be remarked that all observations in shafts thus far have exliibitcd 

 irregularities of this kind. The water in such large openings seems to have 

 its temperature governed by springs and other extraneous causes, rather than 

 by the temperature of the surrounding soil. 



The observations at every 50th foot of depth in the Kentish Town well, as 

 given in previous Reports, are so complete that it has not been thought 

 necessary to continue them. A very delicate thermometer, reading by esti- 

 mation to the -j-Lj- of a degree, has, however, been procured, for taking obser- 

 vations from year to year at one constant depth (1000 feet). It was con- 

 structed ten months ago, and being enclosed in a partially exhausted glass 

 tube, wiU probably not undergo much change of zero. It has been four times 

 tested by comparison Avith standards, and has been foiind to have no error 

 amounting to nearly so much as 0°*1. In consequence of Mr. Symons's 

 illness, no observation has yet been taken with it in the well. 



A Six's thermometer, which, through tlie breaking of a rope, had fallen 

 into the mud at the depth of 1090 feet from the surface of the ground, was 

 extracted by Mr. Symous last November, more than a year after its fall. It 

 had sustained no damage, and its indication when hauled up was 69°-4, 

 nearly agreeing with the temperature previously observed at that depth. 



In addition to the large number of thermometers above mentioned as 

 having been issued during the past year, one has been furnished for obser- 

 vations which are to be made in the projected boring through the Wealden 

 and underlying strata. With the exception of Mr. Symons's observations at 

 Kentish Town (London, N.), we have as yet no observations of temperature 

 from the southern parts of England, 



Preliminary Report of the Committee on Siemens' s Electrical-Resistance 

 Pyrometer, consisting o/ Professor A. W. Williamsox, F.R.S., Sir 

 W. Thomson, D.C.L., F.R.S., and Professor J. Clerk Maxwell. 

 LL.D., F.R.S. 



The experiments of the Committee have hitherto been confined to testing the 

 electrical permanence of the coil of wire used in the pyrometer. For this 

 purpose the resistance of the coil has been repeatedly taken at known 



