FRO 
new them at the same time. Among woody 
plants, the elder, and most of the honey- 
suckles ; among perennial herbs, crocus 
and tulip, are the first that push or expand 
their leaves. The time of sowing the seed 
decides with respect to annuals. The oak 
and ash are constantly the latest in pushing 
their leaves : the greatest number unfold 
them in spring ; the mosses and firs in 
winter. These striking differences, with 
respect to so capital a circumstance in 
plants as that of unfolding their leaves, seem 
to indicate that each species of plant has a 
temperature proper or peculiar to itself, and 
requires a certain degree of heat to extri- 
cate the leaves from their buds, and pro- 
duce the appearauce in question. This 
temperature, however, is not so constant as, 
to a superficial observer, it may appear to 
be. Among plants of the same species, 
there are some more early than others ; 
whether that circumstance depends, as it 
most commonly does, on the nature of the 
plants, or is owing to differences in heat, 
exposure, and soil. In general, it may be 
affirmed, that small and young trees are 
always earlier than larger or old ones. See 
Germination, and Milne’s Bot. Diet. 
FROST, such a state of the atmosphere 
as causes the congelation or freezing of 
water or other fluids into ice. In the 
more northern parts of the world, even 
solid bodies are affected by frost, though 
this is only or chiefly in consequence of the 
moisture they contain, which being frozen 
into ice, and so expanding as water is 
known to do when frozen, it bursts and 
rends any thing in which it is contained, as 
plants, trees, stones, and large rocks. Many 
fluids expand by frost, as water, which ex- 
pands about Jjth part, for which reason 
ice floats in water ; but others again con- 
tract, as quicksilver, and thence frozen 
quicksilver sinks in the fluid metal. 
Frost, being derived from the atmosphere, 
naturally proceeds from the upper parts of 
ho lies downwards, as the water and the 
earth : so, the longer a frost is continued, 
the thicker the ice becomes upon the water 
in ponds, and the deeper into the earth the 
ground is frozen. In about 16 or 17 days 
frost, Mr. Boyle found it had penetrated 14 
inches into the ground. At Moscow, in a 
hard season, the frost will penetrate two feet 
deep into the ground: and Captain James 
found it penetrated 10 feet deep in Charlton 
Island, and the water in the same island was 
frozen to the depth of six feet. Sheffer as- 
sures us, that in Sweden the frost pierces 
FRO 
two cubits, or Swedish ells into the earth, and 
turns what moisture is found there into a 
whitish substance, like ice ; and standing 
water to three ells or more. The same author 
also mentions sudden cracks or rifts in the 
ice of the lakes of Sweden, nine or ten feet 
deep, and many leagues long ; the rupture 
being made with a noise not less loud than 
if many guns were discharged together. By 
such means however the fishes are fur- 
nished with air; so that they are rarely 
found dead. 
The natural history of frosts furnish very 
extraordinary effects. The trees are often 
scorched and burnt up, as with the most ex- 
cessive heat, in consequence of the separa- 
tion of water from the air, which is there- 
fore very drying. In the great frost in 
1683, the trunks of oak, ash, walnut, &c. 
were miserably split and cleft, so that they 
might be seen through, and the cracks often 
attended with dreadful noises like the ex- 
plosion of fire arms. Philos. Trans. Num- 
ber 165. 
The close of the year 1708, and the be- 
ginning of 1709, were remarkable through- 
out the greatest part of Europe, for a se- 
vere frost. Dr. Derham says, it was the 
greatest in degree, if not the most universal 
in the memory of man ; extending through 
most parts of Europe, though scarcely felt 
in Scotland or Ireland. 
In very cold countries, meat may be pre- 
served by the frost six or seven months, and 
prove tolerably good eating. See Captain 
Middleton’s observations made in Hudson’s 
Bay, in the Philos. Trans. Number 465, 
sect. 2. 
In that climate the frost seems never out 
of the ground, it having been found hard 
frozen in the two summer months. Brandy 
and spirit, set out in the open air, freeze to 
solid ice in three or four hours. 
Lakes and standing waters, not above 10 
or 12 feet deep, are frozen to the ground in 
winter, and all their fish perish. But in 
rivers where the current of the tide is 
strong, the ice does not reach so deep, and 
the fish are preserved. Id. ib. 
Some remarkable instances of frost in 
Europe, and chiefly in England, are re- 
corded as below ; in the year 
220 Frost in Britain that lasted five 
months. 
250 The Thames frozen nine weeks. 
291 Most rivers in Britain frozen six 
weeks. 
359 Severe frost in Scotland for 14 
weeks. 
