Page:Cyclopaedia, Chambers - Volume 2.djvu/1019

WEI the English, French, Dutch, Portugueze and Danes, have introduc'd their own Weights in their respective Settle- ments.

The Isle of Madagafcar, indeed, has its particular Weights; but it has none that exceed the Drachm, nor are they us'd for any thing but Gold and Silver—Other Commodities they never weigh.

Antient Weights

Jewish Weights reduc'd to English Troy Weights.

Note, In reckoning Money, 60 Shekels made a Maneh, but in weight 100 Shekels.

Grecian and Roman reduc'd to English Troy Weight.

0 : 00 : 00 : 09 3/28 0 : 00 : 00 : 18 3/14 0 : 00 : 02 : 06 9/14 0 : 00 : 03 : 00 6/7 0 : 00 : 04 : 13 1/7 0 : 00 : 06 : 01 5/7 0 : 00 : 18 : 05 2/7 0 : 10 : 18 : 13 5/7

The Roman Ounce is the English Averdupoifs Ounce, which they divided into 7 Denarii, as well as 8 Drachms; and aince they reckon'd their Denarius equal to the Attic Drachm, this will make the Attic Weights ⅛ heavier than the correspondent Roman Weights.

Note, The Grecians divided their Obolus into Chalci and. Some, as Diodorus and Suidas, divided the Obolus into 6 Chalci, and every Chalcus into 7 Others divided the Obolus into 8 Chalci, and every Chalcus into 8, or Minuta.

The Subdivisions of the Roman As, Libra, or Pound.

Unciæ, or Ounces.

Weight of Air, is equal to the Elasticity thereof. See Air, and Elasticity.

To find the Weight of a Cubic Inch of Air. — Weigh a round glaas Vessel full of common Air, very accurately : exhaust the Air out of it : weigh the exhausted Vessel, and subtract the latter Weight from the former; the Remainder is the Weight of the Air exhausted.

Find, then, the Content of the Vessel by the Laws of Measuring, (see Sphere;) and the Ratio of the remaining Air to the primitive Air. See Air-Pump.

This done, the Bulk of the remaining Air is found by the Rule of Three; which being subtracted from the Capacity of the Vessel, the Remainder will be the Bulk of Air extracted.—Or, if the Air-Pump be very tight, and the Exhaustion continu'd as long as any Air is got out; the remaining Air will be so small, that it may be safely neglected, and the Content of the Vessel taken for the Bulk of the exhausted Air.

Having, therefore, the Weight and Bulk of the whole exhausted Air, the Weight of one Cubic Inch is easily had by the Rule of Three.

This Method was first used by Otto Gueric, and afterwards by Burcheras de Volder; who gives us the following Particulars in his Experiment. — 1$11⁄12$, That the Weight of the Glass spherical Vessel he made use of, full of common Air, was 7 Pounds 1 Ounce 2 Drams 48 Grains; when exhausted of Air, 7 l. 1 osa. 1 dr. 31 gr. and when full of Water, 16 l. 12oz. 7dr. 14 gr. The Weight of the Air, therefore, was 1 dr. 12 gr. or 77gr.the Weight of the Water 9l. 11oz. 5 dr. 43 gr. or 74743 gr. Consequently, the Ratio of the specifick Gravity between Water and Air, is 74743 : 77 : : $5⁄6$ : 1. Now, Volderus, having found a Cubic Foot of Water to weigh 64 Pound ; by inferring, as 970 is to 1, So is 64 Pounds to a fourth Proportional; which found by the Rule of Three is the Weight of a Cubic Foot of Air, viz. 1 Ounce, 27 Gr. or 507 Grains. See Air.

The Weight of Sea Water is different in different Climates. Mr. Boyle having furnish'd a learned Physician, going on a Voyage to America, with a Hydrostatical Balance; and recommended him to observe, from time to time, the difference of Weight he might meet withal; this Account was return'd him : That the Sea Water increas'd, in Weight the nearer he came to the Line, till he arrived at a certain degree of Latitude, as he remembers, about the 30th; beyond which, it retain'd the same specific Weight, till he came to Barbadoes. Philosph.Transact. N$3⁄4$ 18.

Weights of Auncel. See Auncel Weight.

WELDING Heat, a degree of Heat which Smiths give their Iron in the Forge, when there is occasion to double up the Iron, and to weld a Work in the Doublings; so that the Iron dull grow into a Lump thick enough for the Purpose. See Iron, Forging, &c.

It is also used when two Bars of Iron are to be joined together at the Ends, to make a Length. See Heat.

WELL, a Hole dug under Ground, below the Level or Surface of the Water collected in the Strata. See Strata, and Water.

It is usually of a cylindrical Figure, wall'd with Stone, and lined with Mortar. See Spring.

M. Blondel informs the French Academy of a Device they use in the lower Austria, which is incompass'd with the Mountains of Stiria, to fill their Wells with Water, viz. That they dig in the Earth to the depth of 20 or 2 5 Feet, till they come to a clammy Earth, which they bore thro', till the  Waters break forcibly out: Which Water, in all probability,  comes from the neighbouring Mountains, in subterraneous channels. — Cassini observes, that in many Places of Modena and Boulogne, they make themselves Wells by the same Artifice. — Mr. Derham adds, that the like has been sometimes found in England, particularly in Essex.

In the Philosophical Transactions, we are inform'd by Mr. Norwood, that in Bermudas, Wells of fresh Water are dug within 20 Yards of the Sea, and even less, which rise and fall with the Tides, as the Sea it self does.—He adds, that in digging Wells in that Island,they dig till they come almost to a Level with the Surface of the Sea; and then they certainly find either Fresh Water or Salt : If it prove Fresh, yet by digging two or three Foot deeper, they always come at Salt Water. If it be sandy Ground, they usually find Fresh Water; but if hard Lime-flone Rock, salt or brackish. See Fresh Water, &c.

In the Diocese of Paderboen in Westphalia, is a Well which loses it self twice in 24 Hours; returning always, after six Hours absence, with great Noise, and so forcibly as to drive three Mills not far off. The Inhabitants call it the Bolderborn, q. d. the boisterous Spring.—Lay-Well near