stand Sir George's paper correctly, this is under a barometrical pressure of 29.74 inches, and at the temperature of 66° of the common thermometer. Captain Kater, in his remeasurements, reduces the pressure to zero; and consequently the deductions from the two measures are not exactly comparable. The following are the results of Captain K.'s experiments :

It may now be useful to collect under one view the data furnished by Sir George Shuckburgh's experiments, and by the preceding measurements.

• From these data, the weight of a cubic inch of distilled water in a vacuum at 62°, deduced from the cube, appears to be

which is equal to 252,722 grains of the Parliamentary standard.'

We have seen that, according to Sir George Shuckburgh, the weight of the cubic inch was only 252-422 grains: but neither the temperature nor the pressure is the same in both

cases.

An Account of Observations made with the Eight Feet Astronomical Circle, at the Observatory of Trinity College, Dublin, since the beginning of the Year 1818, for investigating the Effects of Parallax and Aberration on the Places of certain fixed Stars; also the Comparison of these with former Observations for determining the Effects of Lunar Nutation. By the Rev. John Brinkley, D.D., &c. We have had several occasions to notice the communications of Dr. Brinkley and our astronomerroyal on the subject of the parallax of certain stars, the summary of which may thus be shortly stated. Dr. Brinkley, from certain observations made with a particular view, discovered anomalies in the places of particular stars, which seemed to indicate an annual parallax: but these cases being -REV. JULY, 1822. examined

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examined by Mr. Pond, he could discover no such irregularities; and hence he concluded that the change of place noticed by Dr. Brinkley must have proceeded from some other cause. Farther correspondence and communication on this subject took place, the leading points of which will be found in several preceding volumes of our Review, where we have noticed those parts of the Philosophical Transactions in which they were published.

The present memoir is likewise composed principally with reference to this inquiry; and, from numerous other observations, Dr. B. still finds reason to assume a parallax in certain stars: at least, he says that he can see no other way of accounting for the anomalies which he has perceived:

All attempts to arrive at results inconsistent with parallax have failed; so that, as far as the new observations are concerned, my former conclusions have been strengthened instead of weakened. I do not mean, however, to assert, that the subject is yet divested of the difficulties attendant on it from other sources. Some of the results that I have found, although in themselves in no manner inconsistent with parallax, will, justly perhaps with many, add to the difficulty of admitting the explanation by parallax. They will be unwilling to admit that many of the smaller stars are nearer to us than many of the brighter; — that in a certain part of the heavens of considerable extent, many of the stars exhibit a sensible parallax. This however must be admitted, if my discordances result from parallax. If it be admitted, then several of the difficulties that have occurred by comparing my observations and those of Mr. Pond will be done away. But I shall defer a few remarks on this head, till I have given an account of my own observations, and of the results thereof.'

As the paper is too long for us to follow the author through the several arguments which he advances in favor of his hypothesis, we shall merely observe that we can see no reason for finding a difficulty in admitting a parallax in some stars of inferior magnitude, although no such effect may be discernible in more brilliant stars. We conceive that, judging from the planets in our system, we have no cause for assuming the brightest stars to be the nearest; and, though we are aware that this is generally supposed, there cannot, we think, be a more groundless assumption.

Some other results in this memoir cannot fail to engage the attention of astronomers. The most remarkable relates to aberration; which seems to indicate that a different constant may be requisite for different stars, or that the velocity of light issuing from different stars is not necessarily the same, though this has been generally supposed.

• The

'The investigation of the constant of aberration by direct observations of zenith distance has not, that I am aware of, been attempted since those of Bradley, by the zenith sector. A century has nearly elapsed since his excellent observations were made. The result s of M. Delambre's investigations relative to the velocity of light, as deduced from the eclipses of Jupiter's satellites, appeared to confirm in so strong a manner the mean of Bradley's results, that astronomers seem to have considered the point quite settled; but if I mistake not, one cause for this was the paucity of instruments adequate to so delicate an enquiry.'

It is unnecessary to observe on the importance of this determination, as connected with the theory of light. Should Dr. Brinkley's suspicions turn out to be well founded, it will be quite decisive against the undulatory system; and it will also shew that the corpuscules theory is insufficient, without the addition of principles as yet unknown, to explain all the phænomena of light.

On the Effects produced in the Rates of Chronometers by the Proximity of Masses of Iron. By Peter Barlow, Esq. of the Royal Military Academy. In our notice of the last volume of these Transactions, Part II., will be found some particulars respecting certain observations made by Mr. Fisher during his Arctic voyage with Captain Buchan, on the rates of chronometers, as they were supposed to be affected by the iron of the ship. That paper seems to have furnished Mr. Barlow with the clue to the experiments detailed in the article before us; the object of which was to ascertain, first, whether iron has really the effect supposed by Mr. Fisher, and, if so, whether it could be reduced to any fixed and determinate laws. With this view, having procured six excellent chronometers, and ascertained their rates by transit-observations, he applied them at different distances, and in different situations, about an iron ball of 13 inches diameter; still taking their rates by transit-observations, as before. He also, while each chronometer retained its place as to distance and situation, changed its own position, by turning first one part towards the iron, and then another; and, by thus continuing his experiments from the beginning of March to the latter end of May, a considerable number of results were obtained, from which the author has derived the following practical deductions:

The first general conclusion which may be drawn from the foregoing experiments, is, that the rate of a chronometer is undoubtedly altered by its proximity to iron bodies.

• Secondly, it appears that it is by no means a general case that iron necessarily accelerates the rate of a chronometer, as would appear from Mr. Fisher's observations; for five out of the six chronometers which I have made use of, were obviously retarded

in

every situation in which they were placed. In one instance only, viz. chronometer No. II., there is an indication of acceleration in one situation; but it is more doubtful than the retardation in all the other five.

:

It is also very obvious from the experiments on Nos. IV. and V. that much depends on the direction of the balance with respect to the iron thus No. IV. lost nearly 2" per day when its 12 o'clock hour mark was turned to the south, and only seventenths when it was placed to the East; but as soon as the chronometer was returned to its old direction, the loss again became 2-1 daily. The same occurred in the case of No. V., which lost 36 per day in one direction, and gained 0"-5 in another at right angles to it; and on returning it again to its former direction, the losing rate became 4"-1 per day, viz. rather stronger than at first. It must be admitted, however, that the same striking difference in the rate, as depending upon direction, was not observed in another instance, when a similar experiment was repeated on the same chronometer. Speaking generally, it also appears, that the greatest effect is produced in those instances where the change in the netic intensity is the greatest; but there does not seem to be that uniformity of relation in these cases, that we should naturally have anticipated.

mag

As a practical conclusion, it is obvious, that on ship-board, great care ought to be taken to keep the chronometers out of the immediate vicinity of any considerable mass or surface of iron; on which account, they ought not to be kept in the cabins of the gun-room officers, which are on the sides of the vessel; and probably a strong iron knee, or even a gun, will be found at a very inconsiderable distance from the spot where the watch is most likely, in this case, to be deposited.

In short, it appears from the preceding experiments, 'that a chronometer ought to be kept as carefully at a distance from any partial mass of iron, as the compass itself. And, as much of the iron of a ship is hidden, the best way of detecting it, and of ascertaining a proper situation for a chronometer, will be to set down a compass in any place designed for the former, and to observe and compare the direction of its needle with that of the azimuth compass on deck, while the vessel is on different tacks; and if the disagreement between the two be very considerable, another situation ought to be selected,

When I made my experiments on local attraction, on board his Majesty's ship Leven, we placed several compasses in different parts of the vessel, some of which were very powerfully affected under different directions of the ship's head; in consequence, no doubt, of their being within the influence of partial action, arising from some near, but hidden, mass of iron.'

Besides the iron ball, Mr. Barlow employed a plate of iron of the kind which he has recommended for correcting the local attraction of a ship's iron on the compass; (see M. R. vol. xcii. p. 18.) from which it appears that, in this case, as in the

18

former,

former, the power of the iron resides wholly on its surface. In consequence, however, of this plate having been unexpectedly sent away to be fitted on board the Fury, (Captain Parry,) for the purpose of correcting the local attraction during his present interesting voyage, the experiments on it were not completed.

Mr. Barlow concludes his paper by explaining the method of determining the ship-rates of chronometers, before they are taken on board; which, if it should be found successful, will be an important datum for nautical men.

The first part of these Transactions for the present year has just appeared.

Hurst

ART. X. Halidon Hill; a Dramatic Sketch, from Scottish History. By Sir Walter Scott, Bart. 8vo. 6s. sewed. and Co. 1822.

Τ

IT is generally the case that much expectation ends in disappointment. The free delineation of character in some of the recent Scotish novels, and the admirable conversations interspersed throughout them, raised hopes that, when a regular drama should be attempted by the person who was considered as their author, the success would be eminent. Its announcement, too, in a solemn and formal manner, did not diminish the interest of the public. The drama, however, which was expected, turns out to be in fact, and not only in name, merely a dramatic sketch; which is entirely deficient in plot, and contains but three characters, Swinton, Gordon, and Edward, in whom any interest is endeavoured to be excited. With some exceptions, the dialogue also is flat and coarse: -and for all these defects one or two vigorous descriptions of battle-scenes will scarcely make sufficient atonement, except in the eyes of very enthusiastic friends.

We conceive it to be extremely probable that Sir Walter Scott had resolved to commemorate some of the events in the life of Wallace, and had already sketched that hero, and a Templar, and Edward the First, when his eye glanced over the description of the battle of Homildon Hill in Pinkerton's History of Scotland; that, being pleased with the characters of Swinton and Gordon, he transformed his Wallace into Swinton; and that, for the sake of retaining his portrait of Edward, as there happened to be a Gordon and a Douglas at the battle of Halidown in the time of Edward the Third, and there was much similarity in the circumstances of the contest, he preserved his Edward as Edward the Third, retaining also

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his