238 



THE FARMER'S MAGAZINE. 



level of the sea, and the mean temperature of the 

 level of the sea, in different latitudes {Banfield and 

 Weld's Stat. Comp., p. 8) : 



Latitude. Congelation. Temperature. 



15,207 84-2 



5 15,095 83-8 



10 14,764 82-6 



15 14,220 807 



20 13,478 78-1 



25 •.. 12,557 74-9 



30 11,484 71-1 



35 10,287 67'0 



40 9,001 62-6 



45 7,671 58-1 



56 6,334 53-6 



55 5,034 49-2 



60 3,818 45-0 



65 2,722 41-3 



70 1,778 38-1 



75 1,016 35-5 



80 457 33-6 



85 117 32-4 



90 000 32-0 



The composition of snow is not quite the same 

 as rain-water. Boussingault examined both rain 

 and snow>water : he found in a gallon of — 



Grains. 



Rain-water, ammonia 0.210 



Snow-water collected on the earth .... 0.454 

 „ collected on a stone terrace 0.080 



There is also a considerable absence of the at- 

 mospheric gases in snow. Fish are said to be 

 unable to live in melted snow-water. 



Hail is another solid form in which the aqueous 

 moisture of the air is deposited on the eartli. 

 Hailstones most commonly are composed of an 

 opaque centre, like compressed snow, encased in 

 another circle of ice. These are usually of about 

 a quarter of an inch in diameter, but they occasion- 

 ally fall of much larger sizes. In very great hail- 

 storms, they have been found two or three inches 

 in diameter, and weighing several ounces. Hail 

 commonly falls before rain storms — often with 

 them ; but very rarely after the rain. The hail- 

 storm is generally of only a few minutes' duration, 

 only very occasionally lasting for a quarter of an 

 hour. 



Various theories have been proposed as explana- 

 tions of the origin of hail. That it is composed of 

 the congealed vapour of the atmosphere, and that, 

 when once the nucleus is formed, the hailstones 

 increase in size, as by the condensation of va- 

 pour they descend, is perhaps the only portion of 

 the enquiry that seems to be generally admitted; 

 and that descent, it is probable, is in some cases 

 so retarded by strong currents of air as to give 

 time for unusual enlargements of the hailstones. 

 The other portions of the investigation are about 

 asmuchunderstoodas when Job asked (x.txviii. 22, 

 29), " Hast thou entered into the treasures of the 

 snow ? or hast thou seen the treasures of hail ? 

 out of whose womb came the ice ? and the hoary 

 frost of Heaven, who hath gendered it ?" 



We have seen, then, that the aqueous vapour, 

 when condensed in the atmosphere, descends upon 

 ua again, in the course of its eternal circles, in a 



drop of rain, a flake of snow, or in still more gently 

 deposited dew : the water has again fallen on the 

 earth, or mingled with its surface waters. In some 

 portions of the sea in fact, as off the coast of Pat- 

 agonia, the rainfall is so copious that the surface 

 of the sea is quite fresh, according to Darwin, from 

 the vast quantity of rain that falls on its surface. 



On the surface of the earth, the rain is partly 

 evaporated from the soil by the winds and sun, or 

 absorbed by the vegetable world, and partly drains 

 away. On many of our cultivated soils, this 

 drainage is aided by artificial means : either by 

 open or surface drains, or by those underground, 

 placed at various depths and distances, according 

 to the varying tenacity of the surface soil, or the 

 substratum on which it rests. 



The proportions of a given quantity of rain 

 which evaporate from, or drain away from dif- 

 ferent soils, have been ascertained by various ex- 

 periments. I have elsewhere given the amount of 

 both these as regards the chalk and limestone soils, 

 by which it will be seen that the evaporation is the 

 greatest on the limestone, and the drainage but 

 small; whilst, on the contrary, the evaporation, 

 as might be expected, is much less considerable on 

 the chalk soils, and the sinking in of the rain far 

 more considerable. 



From clay soils the underground drainage is 

 much more slow, the surface drainage and evapo- 

 ration more considerable. Mr. J. Bailey Denton 

 found on the soils at Hinxworth {Jo?{r. R. A. S., 

 vol. XX., p. 275) that when 227,240 gallons per 

 acre fell upon that estate during eight months, that 

 on the free soils 160,920 gallons of that rainfall 

 found their way into the drains, but from the clay 

 soils only 59,936 gallons per acre. It is these 

 drainage waters which constitute our springs ; and 

 these, when united, increase into the rivers of our 

 globe. Most of these natural underground waters 

 influenced materially in their course by the strata 

 they meet with, they are occasionally diverted from 

 their course during their descent, by meeting with 

 slowly permeable strata; and hence, in rainy sea- 

 sons, long dried-up springs reappear, and pour 

 their waters into lower districts. 



There are certain intermittent springs in the 

 great southern chalk formation of England, which 

 arise from this varying amount of the rain-water 

 descending through the earth. They are rather 

 curious in their movements, and appear at different 

 periods of time. In some places, as at Croydon, 

 Epsom, " the Bourne Mill," near Farnham, and 

 Gatton, near Merstham, they make their appear- 

 ance at intervals of some years t at other places, 

 as at Lewes, in Sussex, and the Winterbournes in 

 Dorsetshire, they flow every winter. These phe- 

 nomena have been explained in more primitive days 

 than ours in a variety of amusing ways. It was 

 supposed, in the times when witchcraft flourished in 

 England, that these bournes were kindly sent to 

 warn us of coming death and sickness. Then it 

 was with equal wisdom imagined that the bourne 

 was vomited forth by a great siphon fancied to 

 exist in the chalk hills, the concoctors of this myth 

 not being aware that siphons do not cause springs 

 to rise higher than their original level, and that 

 Dame Nature does not need their aid to enable 



