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secured and accumulated at sea, where the temperature being least influenced by other climatic concomitants, is alone capable of yielding the desired results.
The observations of temperature made on land have a more humble aim in view, namely, the interests of agriculture, to which they are capable of rendering as important assistance as that which is furnished by chemistry. To the colonies of New South Wales and Van Diemen's Land, where the spirit of enterprise and industry leads the settlers to study the amelioration of the exotic vegetation and breeds of animals, meteorological observations generally, and the knowledge of thermometrical means in particular, will be of most essential service. Thus, if he know the kind of soil, and the mean temperature of Montpellier, Xeres, Malaga, or Oporto, a settler in New South Wales may decide whether the vine or olive tree of those localities is adapted to his own vineyard or orchard. Again, such knowledge may lead him to the introduction of the Alpacca from Peru, or may in some measure be instrumental in correcting the erroneous and unprofitable system which he had previously pursued, of breeding cattle in a locality of a higher winter mean than that from which they were orginally imported.
The colony of New South Wales furnishes, for the deduction of its thermometrical condition, three registers, kept for the three years ending with 1842. Reduced to the last term of their means, these registers give, in degrees of Fahrenheit's thermometer, —
The three stations of the colony of Van Diemen's Land furnish registers of temperature for five years, ending with 1842 ; to which is added my own register, kept in Launceston for one year. Abridged, in a manner similar to the former, these registers give the following results: —
The difference in latitude between Port Macquarrie, the farthest northern station, and Port Arthur, the extreme southern, being = 11° 45', the difference between their respective annual means of temperature will be = 10" 1; and hence the change of temperature on every minute of latitude is = 0-01432624. of a degree of Fahrenheit.
Now, by reducing the annual means of the intermediate stations to this ratio of change of temperature, and by comparing such reduction with the means of actual observations, we obtain a test of the accuracy of the registers.
The differences between the computed and observed means, far from invalidating the observations, do but show the local thermometrical anomalies of each station in a more prominent light, and corroborate what, otherwise, a mere knowledge of the localities would have led to be supposed.
Thus, the station of Port Jackson, situated on a naked cliff of sandstone, exposed to higher calorific effects of solar radiation than the two extreme stations, possesses, consequently, a higher annual mean than that which the ratio of change of temperature between Port Macquarie and Port Arthur assign to its latitude. Woolnorth, on the contrary, being on the level of the sea, surrounded by a thick underwood vegetation and marshy grounds, and thus exposed to an increased frigorific influence, has, and by parity of reasoning must have, its actual mean lower. When, however, the difference between the two annual means is sUght, as in the case of Port Philip, Circular Head, and Launceston, the local condition of such stations and the two extreme ones are alike.
The annual means of the above stations suggest another reflection. The abstract shows that Port Arthur and Circular Head are isothermal: on the examination however of their registers, a most material difference in other circumstances of temperature is observed. They differ in maxima and minima; and the fluctuation of temperature at Port Arthur, is both in winter and summer, nearly double that of Circular Head; thus showing that the annual mean of a locality— upon which so much stress is commonly laid — is, by itself, an element of no value, and is far from conveying a correct idea of the temperature to which it refers.
By comparing the thermometrical condition of the above seven stations with that of various localities in the northern hemisphere, we shall see that the temperature of the former is more admirably adjusted than any with which they may be put in juxtaposition: the fluctuations, for instance, of St. Petersburgh are 57°; of Warsaw, 43-2 ; Vienna, 43°; Buda, 44°; Milan, 38-4; Zurich, 38*9; Copenhagen, 38*9; Philadelphia, 43*3; New York, 55°; Quebec, 59*6; — whereas the highest annual mean of such fluctuation at Port Philip amounts only to 37-3!
Other facts, which the examination of the registers furnish, are —
1. That the temperature between eight and nine oclock, A.m., in summer, and between nine