20 M'Keevor's Voyage to Hudson's Bay. 



whole height of the cavity, the diameter of the sentient ball 

 being likewise nearly the third part of that of the orifice of 

 the cup. In order to separate more the balls of the pyroscope, 

 the gilt one may be carried somewhat higher than the other, 

 and lodged in the swell of the cavity, its stein being bent to 

 the curve, and the neck partially widened to prevent the risk 

 of dividing the coloured liquor in carriage. A lid of the 

 same thin unpolished metal as the cup itself, is fitted to the 

 mouth of the eethrioscope, and only removed when an obser- 

 vation is to be made. The scale may extend to sixty or 

 seventy millesimal degrees above the zero, and about fifteen 

 degrees below it. Should Mr. L.'s anticipations with regard 

 to the utility of this instrument prove to be well grounded, 

 it will prove to be a valuable acquisition indeed to every phy- 

 sical cabinet. The eethrioscope, remarks this fascinating 

 writer, thus opens new scenes to pur view. It extends its 

 sensation through indefinite space, and reveals the condition 

 of the remotest atmosphere. Constructed with still greater 

 delicacy, it may, perhaps, scent the distant winds, and detect 

 the actual temperature of every quarter of the heavens. The 

 impressions of cold which arrive from the north will pro- 

 bably be found stronger than those received from the south. 

 But the instrument has yet been scarcely tried. We are 

 anxious to compare its indications for the course of a whole 

 year, and still more solicitous to receive its reports from other 

 climates, and brighter skies. See Supplement to the Ency- 

 clopcedia Britannica^ Articles Climate and Cold. Also, Trans- 

 actions of 'the Royal Society oj 'Edinburgh, vol. vii. part ii. 



I have been induced to dwell thus long on the proofs 

 which I conceive may be offered in favour of the opinion that 

 the surface of the northern seas is annually subjected to the 

 process of congellation, as on this single circumstance, in a 

 great measure, depends the success of the northern expedition; 

 for if these seas are, as I have endeavoured to prove, annually 

 exposed to the eternal fluctuation of having their surface 

 frozen over, they must for ever present to the intrepid navi- 

 gator obstacles altogether insurmountable.* 



* The reason, I conceive, why so large a body of ice has been detached 

 from the west coast of Greenland is simply this : In consequence of the 

 number of bays, creeks, and inlets, which the coast of Greenland presents, 

 ice will very readily be formed, and will, owing to the shelter which the 

 land affords, in course of time accumulate to an enormous extent. At 

 length, however, from agitation, or from their great weight overcoming the 

 power of cohesion, the key-stone of the mass gives way ; the iey chains 

 which held these frightful masses are dissolved, and the whole is gradually 

 drifted into southern latitudes. 



