254 KEPORT— 1873. 



taking of a complete set of observations on the 15tli, 16th, and I7th of October, 

 as shown in the last of the subjoined columns : — 



It thiis appears that the abnormal elevation of temperature at the bottom 

 due to boriug, was 7^° Fahr. 



With reference to the temiieratures in the first 300 metres, Messrs. Mauget 

 and Lippmann remark : — "When last year's observations were made, the well 

 had been tubed to the depth of 139-15 metres, but had not been cemented. 

 Consequently the sjirings which were met with in the tertiary strata, com- 

 municated, at the base of the tubes, with the water in the well. Cement has 

 this year been poured in between all the tubes, some days before taking the 

 temperature of the water. This operation has excluded the tertiary springs, 

 and permitted the water of the well to resume its normal temperatui'e."] 



At Xentish-Town well, the new thermometer described in last Eeport was 

 lowered by Mr. Symons to the depth of 1000 feet, on October 29th, 1872. 

 It has been raised and read thi-ee times, with the foUowiug results : — 



1872. December 23rd 67-71 



1873. April .5th 67-66 



„ July 5th 67-58 



„ September 5th . , . ., 67-50 



These exhibit a steady decrease, which can scarcely be attributable to errors 

 of observation, as such errors, whether arising from change of length in the 

 copper wire by which the thermometer is sustained, or from change in the 

 thermometer itself, would probably have been in the opposite direction. Mr. 

 Symons writes : — " Tbe scale-error of the thermometer might have changed ; 

 but thermometers read higher by age, not lower, except when in vacuum- 

 jackets, which this is not. Moreover, on roughly comparing it with my Ivew 

 Standard, I find it certainly iiot lower, perhaps higher ; but the comparison 

 of maximum-thermometers in shields with naked standards requires more 

 time than I have yet been able to give." 



As it will be instructive to trace these variations to their source, the tlier- 

 mometer has been removed for retesting, and the depth-measuring ajiparatus 

 for cleaning. Mr. Symons proposes to substitute steel for copper wire, so as 

 to reduce the amount of stretching, to substitute monthlj' for quarterly obser- 

 vations, and to attack the problem with all possible delicacy nest year. 



Mr. Lebour writes, with reference to the observations contained on j^age 133 

 of last year's Eeport, that Mr. Atkinson has " repeated the observations for 

 temperature in the South-Hetton bore-hole, the result being that the abnor- 

 mal temperature at 644 feet from the top of the boring (viz. 75°, that at 

 600 feet being 76|°, and that at 670 feet being 77^°) was found to have 

 been quite accidental, being caused in all probability by insufficient time 



