223 



Annual Reports on the Progress of the Sciences, presented to the 

 Royal Acadenoy of Stockholm in 1836. — By the Academy. 



Maps of the Ordnance Survey of Ireland. — By the Lord Lieu-^ 

 tenant. 



The Quarterly Journal of Agriculture ; and the Prize-Essays and 

 Transactions of the Highland and Agricultural Society of Scot- 

 land. For June, September, and December 1838 — By the 

 Society. 



The following Communication was read : 



Discussion of one Year's Observations of Thermometers sunk 

 to different Depths in different localities in the neigh- 

 bourhood of Edinburgh. By Professor Forbes. 



These observations were ma«le, at Professor Forbes's suggestion, 

 at the expense of the British Association. They are still continued, 

 and the present notice contains only a first approximation to the 

 solution of the problems which they are intended to give. 



The chief aim of the experiments is to ascertain the progress of 

 Solar Heat in the Crust of the Globe, and has no immediate refer- 

 ence to the question of central heat ; the depth to which the expe- 

 riments extend being inadequate to afford decisive results on that 

 head. 



The experiments diflFer in their object from any hitherto made, 

 from having an especial regard to the structure of the soil and the 

 conducting power for heat of diff"ei'ent geological formations. With 

 this view three series of thermometers were constructed by Mr 

 Adie, under Mr Forbes's directions, each nearly of the same length 

 and range, and these were sunk in holes prepared for them to pre- 

 cisely similar depths, (1.) in the Trap Tufa of the Calton Hill, with- 

 in the Observatory grounds ; (2.) in the homogeneous bed of Sand 

 at the Experimental Garden ; and (3.) in the compact Coid Forma- 

 tion Sandstone of Craigleith Quarry, all in the immediate neigh- 

 bourhood of Edinburgh, and within a radius of about a mile. With 

 a view to render these observations more immediately comparable 

 with those made at Paris and Brussels, the extreme depth was the 

 same, or the lowest thermometer had its bulb at the distance of 

 24 French feet (= 23.6 English) below the surface, and the others 

 were placed at each station at depths of 12, 6, and 3 French feet.* 



• At the Observatory a thermo-electric pair of iron and copper wires 



