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Where the air of a room is kept uniformly warm, it must be changing every moment. By being heated, it is rarified and presses upwards; its place is supplied by the cold air from without, which, being more dense, rushes in at every little crevice in the lower part of the room.
The principal advantage arising from the uniform heat of a stove, is, that the walls of the room become warmed, and communicate their warmth to the air which comes into the room, and gets in contact with them. In a room, the walls of which are cold, if the air is heated and rarified, it will be cooled and condensed the moment it comes in contact with the cold walls; and as by condensation it becomes heavier, it will rush downwards, producing a current of air towards the floor, which will be felt by those sitting close to the wall.
You will uniformly see these observations exemplified in assembly rooms and churches, the walls of which, being cold, condense the warm air. By condensation, it parts with the moisture which it held in solution, and which is seen running down
the walls in streams. All rooms which are not meant to be frequently used, such as assembly rooms, ought to be plastered on laths, or, what would be better still, papered, or painted on canvas. In the latter case, at least, I should suppose they never would be so cold as to condense the air, and produce the effects above mentioned.
I must own, I am a friend to warmth. It is said, that by custom, we may inure ourselves to cold, in such a manner as to render our bodies in some degree insensible to it; but supposing this to be attained, it does not follow that its pernicious effects on us are prevented. Rheumatisms, and other diseases, may be the consequence.
The Canadians keep their houses very hot; and they themselves, while excessively warm, go immediately into the cold air, without seeming to feel any inconvenience from it; which would induce one to believe that the sudden transition from a hot room into the cold air, if the person be properly clothed, were not so dangerous as is generally imagined. This is further illustrated by the instances I have formerly mentioned of ladies and gentlemen going
into the cold night air, out of a warm ballwithout suffering any inconvenience
room, from it.
I am disposed to join in the opinion of those who think that the living in a warm room, so far from weakening and making you delicate, as it is termed, and rendering you unfit to bear cold, is the best preservative against the bad effects of cold, when you may be under the necessity of exposing yourself to it.
It has been observed by an eminent philosopher, that if, during the time we are sitting still, the circulation of the blood is gradually and insensibly diminished by the cold which surrounds us, it is not possible that we should be able to support a great additional degree of cold, without sinking under it. We should be like water, which, by exposure to moderate cold in a state of rest, has been slowly cooled down below the freezing point; the smallest additional cold, or a small degree of agitation, changes it to ice in an instant; but water, at a high temperature, will support the same degree of frost, for a considerable time, without appearing to be at all affected by it.
In giving you facts, illustrative of the
severity of a Canadian winter, let me mention to you the experiments on bomb shells, made at Quebec some years ago, by a Major Williams, of the Artillery. I am acquainted here, with some gentlemen who witnessed the experiments: they were made in order to ascertain the force of the expan sion of freezing water: they are curious; and you, perhaps, have not met with them in the course of your reading.
These experiments were made on iron shells of different sizes, from the 13-inch shell, to the cohorn of four inches diameter. The shells were nearly filled with water, and an iron plug was driven in at the fuze hole, by a sledge hammer. It was found, however, that the plug could never be driven so firmly into the fuze hole, as to resist the expanding ice, which pushed it out with great force and velocity, and a bolt or cylinder of ice immediately shot up from the hole: but when a plug was used that had springs, which would expand, and lay hold of the inside of the cavity, so that it could not possibly be pushed out, the force of the expansion split the shell.
The amazing force of expansion in congelation is also shewn from the distance to
which these iron plugs were thrown out of the fuze hole. A plug of two pounds and a half weight was thrown no less than 415 feet from the shell; the fuze axis was at an angle of 45; the thermometer shewed 51 degrees below the freezing point. Here you see ice and gunpowder performing the same operations. That similar effects should proceed from such dissimilar causes is very extraordinary.
The expanding force of freezing water acts powerfully on all bodies exposed to its operation. Wherever water lodges, and is at all confined, as in the cracks and fissures of rocks, or in the walls of houses, the effects of its expansion are felt. Masses of rock are severed from the mountain's brow, and precipitated into the valleys below. There the frost again acts upon them, and they are reduced from one size to another, until they become an earth.In agriculture, the effects of the expansion of freezing water are well known. farmer finds, that by ploughing a strong soil, and exposing it to the operation of the winter's frost, the hard clods are broken down and pulverised, and the soil is better