PRACTICAL METEOROLOGY.] 



METEOROLOGY. 



1159 



entangled and lost in the chaos of jarring effects. The 

 speculative meteorologist finds himself unable to thread 

 the labyrinth of causation here involved. Having 

 shown that the ocean would have been full of ice, had 

 the ordinary law of solidification not been departed from 

 in the case of water, it is perhaps unnecessary to follow 

 the development of our hypothetical case further. That 

 ocean life must have been destroyed is evident ; that the 

 sea's liquid highway would have ceased to be, is only a 

 figurative expression for a frozen ocean. But would 

 what is now the solid land have then served the purposes 

 of animal life 1 Where could the rivers have flown, had 

 the ocean been a block of ice? or would not the rivers 

 have remained frozen too, seeing the vast cooling power 

 of a frozen ocean ? It is easy to see that, under such 

 circumstances, our planet would have been totally unfit 

 to be a resting-place for its present denizens had the 

 freezing of water not assumed a departure from a law, 

 though it be impossible to imagine all the consequences 

 that would have resulted. 



The same expansive force of water during the act of 

 freezing, by the operation of which it is rendered speci- 

 fically lighter than water, subserves many important 

 purposes in the world's economy, besides floating the ice. 

 Water percolating into the fissures of rocks, and being 

 subsequently frozen there, displays its irresistible force 

 by splitting lr ge rocks into fragments, and disintegrating 

 lueir fragments. In this way hard and sterile districts 

 become covered with useful soil, in which low forms of 

 vegetable life can take root ; and by their subsequent 

 decay, contribute the elements necessary to the support 

 of higher forms of vegetation. 



Relation of Climate to Organic Development. The 

 naturalist, who, in his desire to see, as in a dioramic 

 picture, the wonderful characteristics of animal and 

 vegetable types, sighs to think that a vision so glorious 

 will never pass, in reality before his gaze, may at least 

 console himself with the assurance of that great master 

 of philosophic travel, Humboldt, that it is in the power 

 of man's creative faculty, aided by philosophy, to imagine 

 those striking types in the vividness of their truth, 

 gladdening the closet with ideal images of the living 

 features of Nature. 



Even in the narrow region of European travel, the 

 intelligent observer will not fail to see distinctive 

 physiognomies. Passing from the cold green-sward and 

 modest vegetation of our own Islus to the Mediterranean 



shore, a striking change in the aspect of nature meets the 

 view. The sturdy oaks and elms of our own forests 

 disappear ; the absence of smaller grasses removes the 

 green carpet of our meadows ; tall graininacese spring 

 up ; the aloe and the prickly pear bespeak a mixed con- 

 dition of heat and drought ; and the date-palm, barely 

 acclimatised, gives some faint notion of what the charac- 

 teristics of a tropical forest must be. " It would be an 

 enterprise worthy of a great artist," says Humboldt, "to 

 study the aspect and the character of all these vegetable 

 groups, not merely in hot-houses, or in the description of 

 botanists, but in their native grandeur in the tropical 

 zone. How interesting and instructive to the landscape 

 painter would be a work which should present to the eye, 

 first separately, and then in combination and contrast, 

 their leading forms ! How picturesque is the aspect of 

 tree ferns, spreading their delicate fronds above tl.d 

 laurel-oaks of Mexico ; or the groups of plantains over- 

 shadowed by arborescent grasses! It is the artist's 

 privilege, having studied these groups, to analyse tftem : 

 and thus, in his hands, the grand and beautiful fjrm of 

 nature which he would portray, resolves itself, like the 

 written works of men, into a few simple elemeuts." 



When the meteorologist has exhausted his knowledge 

 in the laying out of climatic groups when he has placed 

 in correlation, conditions identical, as he thinks, in every 

 respect the growth of vegetable forms demonstrates his 

 inability to comprehend many hidden secrets of nature, 

 which theirdelicate organisation makes known. European 

 olive-trees grow luxuriantly at Quito, but they bear 

 neither fruit nor flowers: and a similar remark applies 

 to walnut-trees and hazel-nuts in the Isle of France. 

 In India, the bamboo flowers luxuriantly ; but in South 

 America, where it flourishes equally well, so far as 

 general aspect of growth is concerned, so rare an event 

 is the infloration of the bamboo, that during a four 

 years' residence in South America, Humboldt was only 

 enabled to obtain blossoms once. But, perhaps, a still 

 more remarkable example of luxuriant growth, without 

 inflorescence, is furnished by the sugar-cane. The West 

 Indies have come to be considered as the region par 

 excellence of the sugar-cane ; yet it seldom bears flowers 

 there nor indeed does it in any part of the American 

 continent ; thus furnishing a strong presumptive argu- 

 ment in favour of the theory, which asserts, that no 

 variety of the sugar-cane is indigenous to the New 

 World. 



CHAPTER IV. 

 PRACTICAL METEOROLOGY. 



So many amateur meteorologists are now springing up 

 in every direction, that it may be desirable to point out 

 the precautions and reductions necessary, in order to 

 render the raw observations useful to science. The pre- 

 sent paper is, therefore, written to enable the amateur, 

 with as little trouble as possible, to reduce his obser- 

 vations to useful results. 



To the non-meteorologist, such terms as "adopted mean } 

 temperature," "elastic force of vapour," "reduced baro- 

 metric," <tc., unexplained, serve rather to perplex than to 

 enlighten, <>r point outth.it care has been bestowed upon 

 the observations, and that the requisite reductions and 

 precautions had been adopted. 



The first duty of an observer is to procure good instru- 

 ments, and to place them in such positions as may be 

 deemed least likely to be aU'ccted by local circumstances, 

 such as heat from a fire, draughts round a building, tc. 

 Much time is frequently thrown away by using imperfect 

 instruments. When a person purchases a thermometer, 

 he is too apt to consider it correct ; whereas, in many 

 instances, it is far from being accurate. Mr. Hartnup, 

 of the Liverpool Observatory, in his last report, mentions, 

 that amnnj{ the thermometers used by the captains of 

 the merchant service, an error of 4 or 5 is quite common; 



even a thermometer fitted up for taking the temperature 

 of water at different depths, and professing to have been 

 made with care, was found to be 8 in error in one part 

 of its scale. The most curious instance, however, was a 

 barometer which had the following errors : 



At 23 inches was 2-22 inches of the standard. 

 At 28i ,, 1-88 



Atae 073 



At29J 0-30 



At 30 0-02 



At30 +0-33 



At 31 +1-07 



The whole yearly range of pressure seldom reaches 

 two inches, whilst the range in error of this instrument 

 was 3 '20 inches. 



METEOROLOGICAL OBSERVATIONS. In orderto place this 

 portion of the subject in as clear a light as possible, let 

 us suppose that daily observations are made of the baro- 

 meter and its attached thermometer, of the temperature 

 of the air, of the wet bulb thermometer, of self -register- 

 ing maximum and minimum thermometers, of the 

 amount of rain, amount of ozone, temperature on the 

 grass and sunshine, state of electricity, amount and class 



