circle, or is stronger than before.
Repeat this experiment with this difference: let two or three of the
persons forming the circle, instead of holding by the hand, hold each
an uncharged electrical bottle, so that the little balls at the end
of the wires may touch, and observe, after the shock, if these wires
will attract and repel light bodies, and if a ball of cork, suspended
by a long silk string between the wires, a little distance from the
bottles, will be alternately attracted and repelled by them.
TO M. DUBOURG.
_On the Analogy between Magnetism and Electricity._
_London, March 10, 1773._
As to the magnetism, which seems produced by electricity, my real
opinion is, that these two powers of nature have no affinity with
each other, and that the apparent production of magnetism is purely
accidental. The matter may be explained thus:
1st, The earth is a great magnet.
2dly, There is a subtile fluid, called the magnetic fluid, which
exists in all ferruginous bodies, equally attracted by all their
parts, and equally diffused through their whole substance; at least
where the equilibrium is not disturbed by a power superior to the
attraction of the iron.
3dly, This natural quantity of the magnetic fluid, which is contained
in a given piece of iron, may be put in motion so as to be more
rarefied in one part and more condensed in another; but it cannot
be withdrawn by any force that we are yet made acquainted with, so
as to leave the whole in a negative state, at least relatively to
its natural quantity; neither can it be introduced so as to put the
iron into a positive state, or render it _plus_. In this respect,
therefore magnetism differs from electricity.
4thly, A piece of soft iron allows the magnetic fluid which it
contains to be put in motion by a moderate force, so that being
placed in a line with the magnetic pole of the earth, it immediately
acquires the properties of a magnet; its magnetic fluid being drawn
or forced from one extremity to the other; and this effect continues
as long as it remains in the same position, one of its extremities
becoming positively magnetised, and the other negatively. This
temporary magnetism ceases as soon as the iron is turned east and
west, the fluid immediately diffusing itself equally through the
whole iron, as in its natural state.
5thly, The magnetic fluid in hard iron, or steel, is put in motion
with more difficulty, requiring a force greater than the earth to
excite it; and when once it has
If it is driven off thro' the air, it must warm the air, and a thermometer held over the mixture, without touching it, would discover the heat, by the rising of the mercury, as it must, and always does in warm air.Page 81
as you observed in our late conversation, a very general opinion, that _all rivers run into the sea_, or deposite their waters there.Page 84
or Â½ _c_, â _c_, &c.Page 93
the same with that, which, being attracted by, and entering into other more solid matter, dilates the substance by separating the constituent particles, and so rendering some solids fluid, and maintaining the fluidity of others; of which fluid, when our bodies are totally deprived, they are said to be frozen; when they have a proper quantity, they are in health, and fit to perform all their functions; it is then called natural heat; when too much, it is called fever; and when forced into the body in too great a quantity from without, it gives pain, by separating and destroying the flesh, and is then called burning, and the fluid so entering and acting is called fire.Page 112
A finger applied to a weighty suspended bell can at first move it but little; if repeatedly applied, though with no greater strength, the motion increases till the bell swings to its utmost height, and with a force that cannot be resisted by the whole strength of the arm and body.Page 149
| | 27| | 60 | 70 | SSE| WbS | |37 13|62 29|Colour of water | | | | | | | | | | | changed.Page 161
| 66 |NW bW|SW Â½W | 190 | | | | 5 |43 5 |17 25| 67| 65 | 65| 68.Page 175
of your town, and have no copy.Page 179
If this be the case, it might prove a commodious method of transporting from distant countries those delicate plants, which are unable to sustain the inclemency of the weather at sea, and which require particular care and attention.Page 201
_ ex cÃ¦li, aÃ«risque inclementia facta est, quod non habeant hypocausta [_stove-rooms_] & quod non soliciti sunt Itali omnes de auribus, temporibus, collo, totoque corpore defendendis ab injuriis aÃ«ris; et tegmina domorum Veneti disponant parum inclinata, ut nives diutius permaneant super tegmina.Page 203
At first many are apt to think that smoke is in its nature and of itself specifically lighter than air, and rises in it for the same reason that cork rises in water.Page 257
He collected a number of glasses of different sizes, fixed them near each other on a table, and tuned them by putting into them water more or less, as each note required.Page 268
_Description of the Process to be observed in making large Sheets of Paper in the Chinese Manner, with one smooth surface.Page 275
| | a |Man, can.Page 279
In remarking on the history, the master will have fine opportunities of instilling instruction of various kinds, and improving the morals, as well as the understandings, of youth.Page 326
and paid into the public treasury, thence to be dispensed by government for those purposes; ought not every _honest man_ freely and willingly to pay his just proportion of this necessary expence? Can he possibly preserve a right to that character, if, by any fraud, stratagem, or contrivance, he avoids that payment in whole or in part.Page 364
_Hospitals_, foundling, state of in England and France, iii.