or the trap-door bellows,
there is consequently less smoke from the fuel to make soot; then,
though the funnel should be foul, yet the sparks have such a crooked
up and down round about way to go, that they are out before they get
at it). I say, if ever it should be on fire, a turn of the register
shuts all close, and prevents any air going into the chimney, and so
the fire may easily be stifled and mastered.
_The Advantages of this Fire-Place._
Its advantages above the common fire-places are,
1. That your whole room is equally warmed, so that people need not
croud so close round the fire, but may sit near the window, and have
the benefit of the light for reading, writing, needle-work, &c.
They may sit with comfort in any part of the room, which is a very
considerable advantage in a large family, where there must often be
two fires kept, because all cannot conveniently come at one.
2. If you sit near the fire, you have not that cold draught of
uncomfortable air nipping your back and heels, as when before common
fires, by which many catch cold, being scorched before, and, as it
were, froze behind.
3. If you sit against a crevice, there is not that sharp draught of
cold air playing on you, as in rooms where there are fires in the
common way; by which many catch cold, whence proceed coughs,
catarrhs, tooth-achs, fevers, pleurisies, and many other diseases.
4. In case of sickness, they make most excellent nursing rooms; as
they constantly supply a sufficiency of fresh air, so warmed at the
same time as to be no way inconvenient or dangerous. A small one
does well in a chamber; and, the chimneys, being fitted for it, it
may be removed from one room to another, as occasion requires, and
fixed in half an hour. The equal temper too, and warmth of the air
of the room, is thought to be particularly advantageous in some
distempers; for it was observed in the winters of 1730 and 1736, when
the small-pox spread in Pensylvania, that very few children of the
Germans died of that distemper in proportion to those of the English;
which was ascribed, by some, to the warmth and equal temper of air
in their stove-rooms, which made the disease as favourable as it
commonly is in the West Indies. But this conjecture we submit to the
judgment of physicians.
5. In common chimneys, the strongest heat from the fire, which is
upwards, goes directly up the chimney, and is lost; and there
_ _The experiments which our author relates are most of them peculiar to himself; they are conducted with judgment, and the inferences from them plain and conclusive; though sometimes proposed under the terms of suppositions and conjectures.Page 1
_Muschenbroek_'s wonderful bottle.Page 3
EXPERIMENT I.Page 10
_ were electrised _minus_; _i.Page 15
remain in the first bottle.Page 17
The operator, who holds the picture by the upper-end, where the inside of the frame is not gilt, to prevent its falling, feels nothing of the shock, and may touch the face of the picture without danger, which he pretends is a test of his loyalty.Page 21
Water being electrified, the vapours arising from it will be equally electrified; and floating in the air, in the form of clouds, or otherwise, will retain that quantity of electrical fire, till they meet with other clouds or bodies not so much electrified, and then will communicate as beforementioned.Page 26
When a great number of clouds from the sea meet a number of clouds raised from the land, the electrical flashes appear to strike in different parts; and as the clouds are jostled and mixed by the winds, or brought near by the electrical attraction, they continue to give and receive flash after flash, till the electrical fire is equally diffused.Page 29
The extremities of the portions of atmosphere over these angular parts are likewise at a greater distance from the electrified body, as may be seen by the inspection of the above figure; the point of the atmosphere of the angle C, being much farther from C, than any other part of the atmosphere over the lines C, B, or B, A: And besides the distance arising from the nature of the figure, where the attraction is less, the particles will naturally expand to a greater distance by their mutual repulsion.Page 36
And this is constantly observable in these experiments, that the greater quantity of electricity on the pasteboard tube, the farther it strikes or discharges its fire, and the point likewise will draw it off at a still greater distance.Page 37
True gold makes a darker stain, somewhat reddish; silver, a greenish stain.Page 41
a right angle, the two next obtuse angles, and the lowest a very acute one; and bring this on your plate under the electrified plate, in such a manner as that the right-angled part may be first raised (which is done by covering the acute part with the hollow of your hand) and you will see this leaf take place much nearer to the upper than to the under plate; because, without being nearer, it cannot receive so fast at its right-angled point, as it can discharge at its acute one.Page 42
greatest quantity.Page 43
By the word _surface_, in this case, I do not mean mere length and breadth without thickness; but when I speak of the upper or under surface of a piece of glass, the outer or inner surface of the vial, I mean length, breadth, and half the thickness, and beg the favour of being so understood.Page 44
But I suppose farther, that in the cooling of the glass, its texture becomes closest in the middle, and forms a kind of partition, in which the pores are so narrow, that the particles of the electrical fluid, which enter both surfaces at the same time, cannot go through, or pass and repass from one surface to the other, and so mix together; yet, though the particles of electrical fluid, imbibed by each surface, cannot themselves pass through to those of the other, their repellency can, and by this means they act on one another.Page 47
1st, That a non-electric easily suffers a change in the quantity of the electrical fluid it contains.Page 53
 To charge a bottle commodiously through the coating, place it on a glass stand; form a communication from the prime conductor to the coating, and another from the hook to the wall or floor.