Glaciers and Climate of Spitzhergefi. 101 



rendered irregular by numerous circumstances, which no allowance can recti- 

 fy, nor caution prevent *. 



If we diverge from the equator, descend in the ocean, or mount into the 

 atmosphere, we generally encounter a decrease of temperature. If such were 

 regular and uniform, the thermometer would afford a good criterion to deter- 

 mine height^ depths or difference of latitude ; but this method, from numerous cir- 

 cumstances, is quite inapplicable. The irregularity is greatest in the air, aaid 

 in no country is that irregularity greater than in Greenland during the sum- 

 mer months ; for the atmosphere there is subject to greater vicissitudes than, 

 perhaps, in any quarter of the globe. JMr Scoresby states, vol. i. p. 397, " In 

 the Polar Regions forcible winds blow in one place, when at the distance of a 

 few leagues gentle bieezes prevail. A storm from the south, on one hand, ex- 

 hausts its impetuosity upon the gentle breeze blowing off the ice on the other, 

 without prevailing in the least. Ships within the circle of the horizon may 

 be seen enduring every variety of wind and weather, at the same moment ; 

 some under close reefed top- sails labouring under the force of a storm ; some 

 becalmed, and tossing about, by the violence of the waves ; and others plying 

 under gentle breezes from quarters as diverse as the cardinal points." The 

 temperature is as variable as the winds, and is entirely under their influence. 

 It has been observed to undergo a change of many degrees within the small 

 compass of an hour or so. On shore the vicissitudes are still greater, on ac- 

 count of the greater variety of circumstances calculated to produce it. On the 

 sheltered hill side exposed to the sun, the general warmth of summer may 

 be felt, whilst on the opposite side we may be chilled by the cold of winter. 

 By the sea-side, a few vegetables spring up and flourish for a while, but to- 

 wards the interior, neither plant nor animal is seen. Now, it must appear evi.. 

 dent, that if we were to calculate on the height of continual frost by observa- 

 tions of temperature made on such a surface, the boundaries would be more 

 irregular even than the surface of the soil, a physical impossibility. Rome, differs 

 but little from Naples in latitude, and the longitude is nearly the same ; but 

 the temperature of the former in summer is sometimes 12° or 14° higher than 

 that of the latter ; but we are not to infer from that, that the circle of perpe- 

 tual freezing over these differs 2000 or .3000 feet in altitude. 



* Dr Latta seems to be mistaken in supiwsing, that tlie decrease of temperature in the atmos- 

 phere would be regulated by the capacities of the different strata for heat, were it not for the conti- 

 guity of the earth's surface ; because he temperature observetl during ascents in balloons deviates 

 farther from this law than temperatures on mountains usually do. The law of decrease depending on 

 capacity, was first advanced by M. Dalton, afterwards by Professor Leslie, and still more lately adopted, 

 for a time, by Mr Ivory, who was at length convincetl of its insuiliciency, and abandoned it. . The 

 atmosphere, it is true, has only been explored, and that imperfectly, to the height of about four 

 miles. But this partial research leaves no doubt, that the same weight of air in the upper regions 

 contains much more heat than below ; or, tliat the decrease of temperature is much slower than the 

 law of capacity requires. Various reasons may be given for this, and, among others, that heat ra- 

 diates copiously from the lower warmer strata to the dilated colder regions, which, from their cold- 

 ness, will, besides, absorb heat with avidity from the fresh solar rays by ^hich they are penetrated ; 

 for these rays are well known to have lost much of their strength by the time they reach the lower 

 strata. Add to this, that, when currents occur in the upper regions, they usually come from a war- 

 mer climate, and the lower currents from a colder. So that, upon the whole, very good reason may 

 J)egivenwhy the higher atmosphere should bemuch warmer than the law of capacity requircs.~EDiT> 



