Further Observations and Experiments concerning the Two Clocks Above-Mentioned, by the Same

Motion of the Pendulum No 1. gradually decreasing all the while, as the other increased; and in three Quarters of an Hour after, it stopped. I then left the Pendulum of No 1. at Rest, and set No 2. a going, making it describe an Arch of $5^\circ$; it continued to vibrate less and less, till it described but about $3^\circ$; in which Arch it continued to move all the time I observed it, which was several Hours. The Pendulum of No 1. seemed but little affected by the Motion of No 2. I tried these Experiments several times over, without finding any remarkable Difference. The freer the Room was from any Motion (as Peoples walking about in it, &c.) I found the Experiments to succeed the better; and once I found No 2. set a going in $16' 20''$, and No 1. at that time stopped in $36' 40''$. I shall not offer my Opinion to this Honourable Society, concerning the Cause of these Phenomena, or at least not till I have farther examined it by the Help of some more Observations and Experiments. VI. Further Observations and Experiments concerning the two Clocks above-mentioned, by the Same. In the preceding Paper I had the Pleasure to communicate to this Honourable Society, an Account of the extraordinary Influence I observed two Clocks to have upon each other, and which was attended with such Circumstances, as I believe had never before been taken Notice of. I shall now beg Leave Leave to lay before you some farther Observations I have since made, which will, I hope, in great measure, account for the Facts then related. In my former Account I took Notice, that the two Clocks were in separate Cases, and that the Backs of them rested against the same Rail; that the Pendulums, when at Rest, were about two Feet asunder, and weighed about 23 lb each, and were made to move with such Freedom, that a Weight of 3 lb would cause either of the Pendulums to describe an Arch of three Degrees. The most remarkable Particulars then observed in them were these: If the Pendulum of one of the Clocks, which (for Distinction sake) I called No 2. was left at Rest, and that of the other, which I called No 1. was set a going, this would, in about 16 Minutes, communicate so great a Quantity of Motion to No 2. as would make its Pendulum describe an Arch of above two Degrees, and would set the Work a going: That the Motion of the Pendulum of No 1. constantly decreased as that of No 2. increased, and after about 30 Minutes it did not describe an Arch sufficient to free the Teeth of the Wheel from the Pallets, so that the Clock stopped. At the same time the Pendulum of No 2. described an Arch of five Degrees, which was two Degrees more than it would have done, had it not been affected by the Motion of No 1. Upon leaving the Pendulum of No 1. at Rest, and setting No 2. a going, the Pendulum of No 1. was found to be but little affected, and never moved sufficiently to set the Work a going. These seemingly different Effects, which the two Clocks had upon each other, I shall now endeavour to account for. R The Manner in which the Motion is communicated to the Pendulum at Rest, I conceive to be thus: As the Pendulums are very heavy, when either of them is set a going, it occasions by its Vibrations a very small Motion, not only in the Case the Clock is fixed in, but, in a greater or lesser Degree, in every thing it touches; and this Motion is communicated to the other Clock, by means of the Rail, against which both the Cases bear. The Motion thus communicated, which is too small to be discovered but by means of some such-like Experiments as these, will, I doubt not, be judged by many, insufficient to make so heavy a Pendulum describe an Arch of two Degrees, or large enough to set the Work a going; and indeed it would be so, but for the very great Freedom with which the Pendulum is made to move, arising from the Manner in which it is hung. This appears from the very small Weight required to keep it going, which, when the Clock was first put together, was little more than one lb. And if the Weight was taken off, and the Pendulum made to swing two Degrees, it would make 1200 Vibrations before it decreased half a Degree, so that it would not lose the $\frac{1}{3000}$ part of an Inch in each Vibration. Indeed if the Weight was hung on, the Friction would be increased, and the Pendulum would not move quite so freely; but even in that Case it was found to lose but little more than the $\frac{1}{2000}$ part of an Inch, or about three Seconds of a Degree, in one Vibration; and therefore if the Motion communicated to it from the other, will make it describe an Arch exceeding three Seconds, the Vibrations must continually increase till the Work is set a going. And And that the Motion is communicated in the manner above supposed, is confirmed by the following Experiments: A Prop was set against the Back of the Case of No 2. to prevent its bearing against the Rail; and No 1. was set a going; then observing them for several Hours, I could not perceive the least Motion communicated to No 2. I then set both the Clocks a going, and they continued going several Days; but I could not find they had any Influence upon each other. Instead of the Prop against the Back of the Case, I put Wedges under the Bottoms of both the Cases, to prevent their bearing against the Rail; and stuck a Piece of Wood between them, just tight enough to support its own Weight. Then setting No 1. a going, I found the Influence so much increased, that No 2. was set a going in less than six Minutes, and No 1. stopped in about six Minutes after. In order to try what Difference would arise, if the Clocks were fixed on a more solid Floor, I placed them (exactly in the same manner as in the last Experiment) upon the Stone Pavement under the Piazza's of the Royal Exchange, and stuck the Piece of Wood between them, as before; and setting No 1. a going, the only Difference I could perceive, was, that it was 15 Minutes before No 2. was set a going, and No 1. continued going near half an Hour before it stopped. From these Experiments I think it plainly appears, that the Pendulum which is put in Motion, as it moves towards either side of the Case, makes the Pressure upon the Feet of the Case to be unequal, and, by its Weight, occasions a small Bearing or Motion in the Case on that Side towards which the Pendulum is moving; and which, by the Interpo- sition of any solid Body, will be communicated to the other Clock, whose Pendulum was left at Rest. The only Objection to this, I conceive, is the differ- ent Effects which the two Pendulums seemed to have upon each other. But this I hope to explain to Satis- faction. For, notwithstanding these different Effects, I soon found, by several Experiments, that the two Clocks mutually affected each other, and in the same Man- ner, though not with equal Force; and that the Varieties observed in their Actions upon each other, arose from the unequal Lengths of their Pendulums only. For, upon moving one of the Clocks to another Part of the Room, and setting them both a going, I found that No 2. gained of No 1. about one Minute 36 Seconds in 24 Hours. Then fixing both against the Rail, as at first, I set them a going, and made the Pendulums to vibrate about four Degrees; but I soon observed that of No 1. to increase, and that of No 2. to decrease; and in a short time it did not describe an Arch large enough to keep the Wheels in Mo- tion. In a little time after it began to increase again, and in a few Minutes it described an Arch of two Degrees, and the Clock went. Its Vibrations con- tinued to increase for a considerable time, but it never vibrated four Degrees, as when first set a going. Whilst the Vibrations of No 2. increased, those of No 1. decreased, till the Clock stopped, and the Pen- dulum did not describe an Arch of more than one Degree 30 Minutes. It then began to increase again, and No 2. decreased, and stopped a second time, but was set a going again, as before. After this No. 1. stopped a second time, and the Vibrations continued to decrease till the Pendulum was almost at Rest. It afterwards increased a small matter, but not sufficiently to set the Work a going. But No. 2. continued going, its Pendulum describing an Arch of about three Degrees. Finding them to act thus mutually and alternately upon each other, I set them both a going a second time, and made the Pendulums describe as large Arches as the Cases would permit. During this Experiment, as in the former, I sometimes found the one, and at other times the contrary Pendulum to make the largest Vibrations. But as they had so large a Quantity of Motion given them at first, neither of them lost so much during the Period it was acted upon by the other, as to have its Work stopped, but both continued going for several Days without varying one Second from each other; though when at a Distance, as was before observed, they varied one Minute 36 Seconds in 24 Hours. Whilst they continued thus going together, I compared them with a third Clock, and found that No. 1. went one Minute 17 Seconds faster, and No. 2. 19 Seconds slower, than they did when placed at a Distance, so as to have no Influence upon each other. Upon altering the Lengths of the Pendulums, I found the Period in which their Motions increased and decreased, by their mutual Action upon each other, was changed; and would be prolonged as the Pendulums came nearer to an Equality, which from the Nature of the Action it was reasonable to expect it would. This discovers the Reason why the Pen- dulum of N° 2. when left at Rest, would be set a going by the Motion of N° 1. whereas if N° 1. was left at Rest, it would not be set a going again by the Motion of N° 2. For I found by several Experiments, that the same Pendulum, when kept in Motion by a Weight, would go faster, than when it only moved by its own Gravity. On this Principle, which may easily be accounted for, it follows, that during the Time in which the shortest Pendulum, N° 2. was only acted upon by N° 1. it would move slower, and the Times of its Vibrations approach nearer to an Equality with those of N° 1. than after it came to be kept in Motion by the Weight; and by this means the Time which N° 1. would continue to act upon it, would be prolonged, and be more than was required to make the Pendulum describe an Arch sufficient to set the Work a going. But on the contrary, while the Pendulum of N° 1. which was the longest, was only acted upon by N° 2. as it would move slower, the Difference of the Times of the Vibrations would be increased; and consequently the Time which N° 2. would continue to act upon it, would for this Cause be shortened, so that before the Pendulum of N° 1. would describe an Arch sufficient to set the Work a going, the Period of its being acted upon would be ended, and it would begin to act upon N° 2. at which time its Vibrations would immediately decrease, and continue to do so till it came to be almost at Rest. And thus it would continue sometimes to move more, and at other times less, but never sufficiently to set the Clock a going. This Account might be confirmed by many more Experiments I have made relating to this Subject; but as I hope these already mentioned will be thought sufficient to confirm the Truth of what I have advanced, I shall forbear to trespass any longer on your Time, and subscribe myself Your most obedient humble Servant, John Ellicott. VII. The Case of a Wound in the Cornea of the Eye being successfully cured by Mr. Tho. Baker, Surgeon to St. Thomas's Hospital, and by him communicated to the Royal Society, in a Letter to Dr. Mortimer, R. S. Secr. A Young Woman, about the Age of 15 Years, on the 6th Day of November 1733, received a Wound just in the Pupil of her right Eye, by the Spear of a common Fork. An Inflammation followed, with great Pain. The whole Eye appeared dark and turbid; and the Humours seemed confused, and blended together. I opened a Vein in the Arm, and drew away 10 Ounces of Blood: I then washed the Eye with a Collyrium of Trochisci Albi Rhasis, and common Water, made Blood-warm; and dressed it with a Cataplasm of white Bread and Milk, with a little Saffron in it. The next Day there appeared