An Observation of the Magnetic Needle Being So Affected by Great Cold, That It Would Not Traverse; By Capt. Christopher Middleton, F. R. S.

This last Observation may be applied to the cooling of Liquors where no Ice is to be had; for there is hardly any Place, but what has Wells: Now the Water of a Well moderately deep, wants about eight or ten Degrees of the Cold of Ice; and Sal Ammoniac being cool'd beforehand in the Well, will, by mixing with some of the Water of that Well, come very near to the Cold of Ice. III. An Observation of the Magnetic Needle being so affected by great Cold, that it would not traverse; by Capt. Christopher Middleton, F. R. S. In a Letter which was publish'd some Years ago in the Philosophical Transactions, (N° 418.) I made Mention of a strange Phenomenon relating to the Sea-Compass, which I had frequently observed, when we were among the Ice in Hudson's Bay; to wit, that the magnetic Virtue of the Needle was so far lost or destroyed, that it would not traverse as usual, even when the Ship was in a considerable Motion: And in my Voyage thither last Year, I observed our Compass would not move at all, any longer than the Quarter-Master kept touching it. We had then much Snow on the Land, and many Isles of Ice around us, and the Sea not very smooth: I order'd one of the Compasses to be brought into the Cabin, but did not find it any better, till it had stood near the Fire about a Quarter of an Hour, and then it began to traverse very well; I then order'd it to be placed in the Binnacle, nacle, and another to be brought into the Cabin, changing them alternately thus every Half Hour, and found by this Means I could make them traverse as well as in any other Part of the World: I was obliged to continue this Practice, till we got near 100 Leagues from the Coast; but afterwards I had no Occasion for that Trouble. What should be the Cause of this wonderful Phenomenon, I am not able to conjecture, being certain the Compasses, as to their mechanical Structure, were very perfect, and answer'd very well both before and after, during the whole Voyage; there is never any Oil used to make them move easily, for in that Case it might often congeal, and stop the Motion of the Chard: But whether the Cold of the Climate hath a Power to deprive the Needle of its Virtue for a Time, or that the Friction is increas'd thereby to such a Degree, as it cannot be overcome by the Magnetism, I am not able to say; but the Fact is certain and surprizing. April 20. 1738. IV. Extract of a Letter from Dr. Andrew Cantwell of Montpelier, to Dr. Thomas Stack, dated June 23. 1732. concerning an uncommon Palsey of the Eye-lids. June 7. 1732. Mons. Guilliminet, Counsellor of the Court of Aides, went hence to Balleruc, (whither I had been call'd to attend a Patient) with a Nun his Daughter, about 30 Years of Age. This Lady was troubled with as singular a Disease as I have heard of. 'Twas an intermitting periodical Palsey of