Imágenes de página
PDF
ePub

As two dark clouds, when mix'd in middle air, r
The vivid lightning's flash, and roar sublime.
Talk not of what is past, but future love.

De Mon. (With dignity.) No, Freberg, no, it must not. (7*
Rezenvelt.) No, my lord.
I will not offer you an hand of concord
And poorly hide the motives which constrain me.
I would that, not alone these present friends,
But every soul in Amberg were assembled,
That I, before them all, might here declare
I owe my spared life to your forbearance.

{Holding out his hand.) Take this from one who boasts no feeling warmth, But never will deceive.

(Jane smiles upon De Monfort -with great approbation, and Rfr' zenvelt runs up to him with open arms.) Rez. Away with hands! I'll have thee to my breast. Thou art, upon my faith, a noble spirit!

De Mon. (Shrinking lack from him.) Nay, if you please, I am not so prepar'd— My nature is of temp'rature too cold—

I pray you pardon me. (Jane's countenance changes.)

But take this hand, the token of respect;

The token of a will inclin'd to concord:

The token of a mind that bears within

A sense impressive of the debt it owes you;

And cursed be its power, unnerv'd its strength,

If e'er again it shall be lifted up

To do you any harm.

Rez. Well, be it so, De Monfort, I'm contented;
I'll take thy hand since I can have no more.
(Carelessly.) I take of worthy men whate'er they give.
Their heart I gladly take; if not, their hand:
If that too is withheld, a courteous word,
Or the civility of placid looks;
And, if e'en these are too great favours deem'd,
'Faith, I-can set me down contentedly
With plain and homely greeting, or, God save ye!

(De Monfort aside, starting away from him some paces.)
By the good light, he makes a jest of it!'

The volume is prefaced with some very sensible observations on the several provinces of the drama, which we have perused with attention and pleasure: but we have not room to make extracts from them, and can only recommend them to the notice of the reader. ,

F 3 Art.

Art. VIII. Philosophical Transactions of the Royal Society of London, Part I. for I798. [Article concluded from Rev. for August, p. 422.J

Mathematical and Philosophical Papers continued.

Account of some Endeavours to ascertain a Standard of Weight and Measure. By Sir George Shuckburgh Evelyn, Bart. F.R.S.

1 N this elaborate paper, consisting of 50 quarto pages, we have a minute account of the speculations and experiments of the ingenious author, on the subject of an universal and perpetual standard of weight and measure. A pendulum has been proposed as a very convenient instrument for this purpose: but many difficulties occurred in determining the actual centre of motion and of oscillation. In order to avoid these, Sir George, so long ago as the year 1780, conceived the idea of 'a pendulum with a moveable centre of suspension, capable of such adjustments as to be made to vibrate any number of times in a given interval; and, by comparison of the difference of the vibrations with the difference of the lengths of the pendulum, (which dilferer.ee alone might be the standard measure,) to determine its positive length, if that should be thought preferable, under any given circumstances.' "While he was deliberating how such a pendulum might bd connected with a piece of mechanism, so ti to number the vibrations without affecting them, he learnt that Mr. Whitehurst had accomplished the object. He therefore directed his subsequent attention towards verifying and completing the experiments of that ingenious philosopher; and with this view, he procured an excellent apparatus adopted to his purpose. Besides the machine with which Mr. Whitehurst had made his observations, (of which he obtained a temporary use,) his other instruments were a beam-compass, or divided scale, made by Mr, Troughton, and furnished with microscopes and micrometer, for the mqst exact observations of longitudinal measure, and also a very nice beam or hydrostatic balance, sensible with the TJ9 of a grain, when loaded with 6 lb. Troy at each end; an admirable time-keeper constructed by Mr. Arnold j a solid cube of brass, whose sides were 5 inches, a cylinder of the same metal, 4 inches in diameter and 6 inches high, and a sphere of brass, 6 inches in diameter. .

After having described, with the assistance of figures, the several parts of his apparatus, Sir George proceeds to give a particular account of the experiments which he made with them, and of the various circumstances to which his attention was directed, that he might avoid the minutest error in his conclusions. He began with ascertaining the difference of the length' of Mr.Whitehurst's pendulums, vibrating 42 and 84. times in a minute, by Mr. Troughton's divided scale. He then investigated the weight of a cubic inch of distilled water, in a knownstate of the atmosphere. His next object was to determine the' proportion of these weights and measures to those that havebeen usually considered as the standard of this kingdom. The" chief authoritative standards of longitudinal measure are those1 preserved in the Exchequer, in the House of Commons, at^ the Royal Society, and in the Tower. Of these several standards, the author has given a very particular account. He;' observes that the first alone bear legal authority, and have been, in use for more than 200 years 5 the last are considered as a" copy of them. The two others arc of modern date, and bear'' no statuteable authority but, as they were made by Mr.'G.* Graham and Mr. J. Bird, artists of acknowleged reputation, they are held in high respect. The mean length of Mr. Graham's , standard made in 1742, compared with the scale divided by Mr. Troughton, was found to be 35,9073 inches. The standard of Mr. Bird made in 1758, compared with Mr. Troughton's1 divisions, was — 36,00023 inches, the thermometer being at 64°. From a table exhibiting a comparative view of the Exchequer standard of 1588 and of Mr. Troughron's scale, it appears 'that the antient standards of the realm differ very little from those'that have been made by Mr. Bird, or Mr. Troughton, and' consequently, even in a finance view, (if one might look 40 far forward,) nothing need be apprehended, of loss in the customs, or excise duties, by the adoption of the latter.'

The author proceeds to shew the proportion of the weights which he used, compared with the standards that were made by Mr.Harris, assay-master of the Mint, under the orders of the House of Commons, in the year 1758. The mean weight of the Troy pound, which was the standard adopted by Mr. Harris, appeared to be 5763)715 grains by Mr.Troughton's weights, the barometer being at 29,72 inches and thermometer 67"; and the mean weight of the 2 lb. Troy, the thermometer being 68°, was 11527,70 grains, and 1 lb = 576^,85 grains; . consequently the mean weight of 1 lb. is deduced from all the trials to be 5763,78 grains: so that Mr.Troughton's weights are too light by 1 in 1523,92 grains. On the whole, our author concludes that the difference of the length of two pendulums, such as Mr. Whitehurst used, vibrating 42 and S4 times in a" minute of mean time, in the latitude of London, at 113 feet above the level of the sea, in the temperature of 6o°, and the barometer being at 30 inches, is = 59>89358 inches of the parliamentary standard j whence all the measures of superficies

F 4 and

and capacity arc deducible. He has also determined thati agreeably to the same scale of inches, a cubic inch of pure distilled water, when the barometer is 29,74 inches, and the ther-. roomier is at 66°, weighs 252,587 grains by Mr.Troughton's weights 5 or, on account of the correction above stated to be necessary of 1 in 1523,92 grains, 252,4,2 parliamentary grains; whence all the other weights may be derived. The three objects which the author has accomplished, by the elaborate investigation contained in this paper, are briefly as follow i

« First an invariable, and at all times communicable, measure of Mr. Bird's scale of length, now preserved in the House of Commons; which is the same, or agrees within an insensible quantity, with the antient standards of the realm. 2dly, A standard weight of the same character, with reference to Mr. Harris's Troy pound. 3dly, Besides the quality of their being invariable, (without detection,) and at all times communicable, these standards will have the additional property ©f introducing the least possible deviation from antient practice, or J inconvenience in modern use.'

Sir George closes this curious paper with a table exhibiting the prices of various necessaries of life, together with that of day-labour, in sterling money, and also in decimals, at different periods from the Conquest to the present time, derived from respectable authorities; with the depreciation of the value of money inferred from them :—To which is added, the mean appreciation of money, according to a series of intervals of 50 years, for the first 600 years, and during the present century, at shorter periods, deduced by interpolation. This table is the result of judgment and labour, and contains, in a small compass, much curious and interesting information.

In an appendix, we have an account of 3 other scales, divided into inches or equal parts, and executed by the late Mr. Bird; one was the property of General Roy, the second belonged to Mr. Harris of the Tower, and is now in the possession of Alex. Aubert, Esq.' and the third was presented byMr. Bird's executors to the Royal Society. These are compared with Mr.Troughton's scale. We have also an examination of the standard rod of Henry VII. constructed about the year 1490, and a comparative view of the lengths of 8 several standards and scales, reduced to one and the same measure, viz. that of Mr. Troughton.

To the class of Philosophical Papers we may refer the usual Abstract of a Register of the Barometer, Thermcnuter, and Raint at Lyndon, in Rutl.ind, for the Tear 179ft •' Thomas Barker, Esq. and the Meteorological Journal of the Royal Society for 1797.

Anatomical Anatomical and Chemical Papers.

Observations on the Foramina Thibesii of the Heart. By Mr* John Abernethy, F. R. S. By adverting to the circumstances under which the principal coronary vein terminates in the right auricle of the heart, we shall readily perceive that the flow of blood through that vessel must be occasionally impeded; and that the difficulty will be much increased, when the right side of the heart is more than ordinarily distended, in consequence of any obstruction to the pulmonary circulation. Such an obStruction, by distending the right side of the heart and hindering the circulation in its nutrient vessels, must probably produce disease in it, if it were not prevented by that structure of the animal ceconomy which the author explains in this paper. On eight comparative trials, mads by injecting the vessels of hearts taken from subjects whose lungs were either much diseased, or in a perfectly sound state, he found that, in th« former, common coarse waxen injection readily flowed into ail the cavities of the heart, but principally into the left ventricle; while, in many of the latter, he could not impel the least quantity of such injection into that cavity. When the left ventricle was opened, and the injection removed, the foramina. Thebesii appeared both numerous and large, and distended with the different coloured wax, which had been impelled into the coronary arteries and veins. In a natural state of the heart, the principal foramina Thebesii are to be found in the right cavities of that organ: but these cavities, even in a state of health,, being liable to an uncommon distention in consequence of muscular exertion, which sometimes forces the venous blood into the heart faster than it can be transmitted through the lungs, similar openings on the left side become necessary; which openings, in their natural state, are capable of emitting blood, and of relieving the plethora of the coronary vessels, and yet are not of sufficient size to give passage to common waxen injections :—but, in a distended state of the right cavities of the heart, which is almost certainly occasioned by a diseased condition of the lungs, these foramina, leading into the left cavities, become enlarged; and thus the plethoric state of the nutrient vessels of the heart, and the consequent disease of that important organ, are prevented. Thus the ingenious author acr counts for the variety that occurs in the size and situation of these foramina, which appear to belong both to the arteries and veins. The injection which was employed was too coarse to pass from one set of vessels to the other, and yet the different coloured injections passed into the cavities of the heart unmixed.

3 ?n

« AnteriorContinuar »