An Invention for Estimating the Weight of Water in Water with Ordinary Ballances and Weights

PHILOSOPHICAL TRANSACTIONS. August 16. 1669. The Contents. An Invention for Estimating the Weight of Water in Water with ordinary Balances and Weights. An Extract of a Letter containing an Account of a passage by sea to the East-Indies. Some Considerations about Slate. Observations concerning the odd Turn of some Shell-snails, and the Darting of Spiders. An account of some Books. I. GEORG. SINGULARIS ARS NOVA et MAGNA GRAVITATIS et LEVITATIS. II. OBSERVATIONES MEDICAE, &c. Musae THOMÆ BARTHOLINI. III. OTTON. TACHENII HYPOCRATES CHYMICUS. IV. TH. BARTHOLINI Dissertatio de CYGNI ANATOME, nunc aucta à CASP. BARTHOLINO F.V. AEGIDI STRAUCHII BREVIARIUM CHRONOLOGICUM. VI. ABREGE CHRONOLOGIQUE de L'HISTOIRE SACREE et PROFANE, par le P. LABBE. An Invention For Estimating the Weight of Water in Water with ordinary Balances and Weights. The Author of this Invention is the Noble Robert Boyle; who was pleas'd to comply with our desires of communicating it in English to the Curious in England, as by inserting the same in the Latin Translation of his Hydrostical Paradoxes he hath gratified the Ingenious abroad. And it will doubtless be the more welcome, for as much as no body, we know of, hath so much as attempted to determine, How much Water may weigh in Water; and possibly if such a Problem had been propos'd, it would have been judged impracticable. The Method or Expedient, he made use of to perform it as near as he could, may be easily learned by the ensuing account of a Tryall or two, he made for that purpose, which among his Notes he caused to be registred in the following words. A Glass-bottle of about the bigness of a potters-egg was purposely blown at the flame of a Lamp, with a somewhat long stem turn'd up at the end, that it might the more conveniently be broken off. This Bubble being well heated to rarify the Air, and thereby drive out a good part of it, was nimbly sealed at the end, and by the help of the figure of the stem was by a convenient Weight of Lead depressed under water, the Lead and Glass being tyed by a string to one Scale of a good Ballance, in whose other there was put too much weight, as sufficed to counterpoise the Bubble, as it hung freely in the midst of the water. Then with a long Iron forceps I carefully broke off the sealed end of the Bubble under water, so as no Bubble of Air appear'd to emerge or escape through the water, but the liquor by the weight of the Atmosphere sprung into the un-replenish't part of the Glass-bubble, and fill'd the whole cavity about half full; and presently, as I foresaid, the Bubble subsided and made the Scale, twas fasten'd to, preponderate so much, that thereneeded 4 drachms and 38. graines to reduce the Ballance to an Equilibri-um. Then taking out the Bubble with the water in't, we did, by the help of the flame of a candle, warily apply'd, drive out the water (which otherwise is not easily excluded at a very narrow stem) into a Glass counterpoised before; and we found it, as we expected, to weigh about 4 drachms and 30 graines, besides some little that remained in the Egg, and some small matter that may have been rarified into vapors, which added to the piece of Glass that was broken off under water and lost there, might very well amount to 7, or 8. graines. By which it appears not only, that water hath some weight in water, but that it weighs very near * or altogether as much in Water, as the self same portion of liquor would weigh in the Air. The same day we repeated the Experiment with another sealed Bubble, larger than the former (being as big as a great Hen-egg,) and having broken this under water, it grew heavier by 7 drachms and 34. graines; and having taken out the Bubble, and driven out the water into a counterpois'd Glass, we found the transvasated liquor to amount to the same weight, abating 6 or 7 graines, which it might well have lost upon such acccompts, as have been newly mentioned. An Extract of a Letter Written by Mr. Joshua Childrey to the Publisher, containing an Accomp of a passage by sea to the East-Indies, communicated to him by that Ingenious Travailor Mr. Richard Smithson Who made two voyages into those parts. From England to Cape Finis Terra in Gallicia in 44. degr. North Lat., the Winds are as variable as with Vs; onely the Bay of Biscay is more subject to storms, and the Sea more rough, and the Waves running very high. From thence to 34. degr. The Wind is variable also, but if you be within 100 leagues of the European Continent, it is generally inclined to North-East. From 34 degrees, if you be inclining to the coast of Africa, or about the Meridian of the Canaries, the Wind is so certain, and constantly at North-East (or within two points) that it is rare to find it otherwise. Yet in Winter, upon the coast of Africa there are sometimes Westerly storms, that are violent, but of no long continuance. And in Summer, when it is sometimes calm, the Air will come variably. These North-East-Winds hold most commonly to 8. degrees North-Latitude, and then begin the Tornado Winds, which are most part confined between 8. and 4. degrees North-Latitude. They are sel-