EXPERIMENTS ON SUBTERRANEAN TEMPERATURE. 



293 



cord exactly their indications under the conditions mentioned m 

 the following table ; of which separate copies have been furnished, 

 so as to have all the entries as uniform as possible, and duph- 

 cates to enable the observers to retain a copy. The original 

 is to be folded and forwarded to " Professor Phillips, Assistant 

 General Secretary to the British Associatio7i, York. 



Weekly Register of Observations on Subterranean Temperature 

 at in Lat. , Long. 



Elevation of the surface above the sea in feet*. 

 Mean annual temperature of the air at surface. 

 Mean temperature of permanent springs issuing from rock. 



* The half-tide level is supposed to be the best standard of sea level : the elevation 

 of the suiface may be found by levelling, trigonometry, the barometer, or by com- 

 parison -with navigations or railways. The method of determination should be stated. 



t The quality of water should be stated, as salt, chalybeate, ordinary. 



t State whether the rock be argillaceous, calcareous, or arenaceous. If experiments 

 be made in rock dykes or mineral veins, another thermometer should be placed at the 

 same depth in the neighbouring rock. 



