learne: And the second cause is this, that sothly me semeth better to writen unto a child twice a good sentence, than he foryete it once. And Lowis, if it so be that I shew thee in my lith English, as true conclusions touching this matter, and not only as true, but as many and subtill conclusions, as ben yshewed in Latine, in any common treatise of the Astrolabie, conne me the more thanke, and pray God saue the king, that is lord of this langage, and all that him faith beareth and obeyeth, eueriche in his degree, the more and the lasse. But considereth well, that I ne usurp not to haue founden this work of my labouror of mine engine: I nam but a leaud compilatour of the labour of olde Astrologiens, and haue it translated in mine English, only for thy doctrine: and with this swerde shall I sleen enuie."

Chaucer does not seem to have finished this work, for in the beginning he divided it into six parts, of which only the first and second, (at most,) have been either finished by him, or else preserved to us. He says that the third part "shall contayne diuers tables of longitudes and latitudes of sterres, fixe in the Astrolabie; and tables of the declinations of the sun, and tables of the longitude of citties and townes and tables as well for the gouernation of the clocke, as for to finde the altitude meridian," &c. Nothing of this appears in the work, which consists of a description of the instrument called the astrolabe, and directions how to use it.

Mr. Peacock, in that excellent and enormous pile of researches which is called by the simple name of " Arithmetic," in the Encyclopaedia Metropolitana, treating of the introduction of the Arabic numerals into England,

has quoted Chaucer's poetry, to prove that he had the newe figures," as he denominated them, about 1375; and argues that the phrase, "newe figures," does not necessarily imply very recent introduction, as that title might stick by them for a century. Granting this, we are rather inclined to think that the words "newe figures' were either introduced for the sake of the measure, or to avoid scientific terms in poetry, for, in this treatise on the astrolabe, Chaucer speaks of the Arabic numerals as the "numbers of augrime, that deuiden thilke same degrees fro fiue to fiue," and that "the numbers of the signs of the degrees been written in augrime." Augrime is the corruption from the Arabic that we now write algorithm, and all the more ancient books on the Arabic numerals specified those numbers by that title.

Chaucer died in the year 1400, at the age of 72.

V.-Nomenclature of the stars. Up to the time of Bayer, (A. D. 1603), it is supposed that the stars were never otherwise distinguished in Europe than either by their Arabic names, such as Aldebaran, Rigel, &c., or by their positions with respect to the constellation, such as, "in the head of Andromeda," "the first in the belt of Orion," &c. The maps of the well-known (by name) Bayer have gained him immortality at no great price, simply from his employing the letters of the Greek and Roman alphabets to distinguish the stars. The idea, if original, was improved by himself before the end of his life, as appears from the joint edition by himself and Julius Schiller, in which numbers are substituted. But, in our time, Bayer is only known by his letters, and the numbers employed are those given by Flamsteed, Piazzi, &c.

It has escaped the notice of all the historians of astronomy, that letters had been used to distinguish one star from another, before the time of Bayer, by Alexander Piccolomini, of Siena, who was successively Bishop of Patras, and Archbishop of his native place. This Piccolomini was a very miscellaneous writer. He was reckoned one of the best comedians of his day, and wrote commentaries on Aristotle, and various other works, besides the one in question. The third edition of his treatise "Della Sfera del Mondo," accompanied by his work "Delle Stelle Fisse," was published at Venice in 1553; and throughout the whole of the latter he employs the italic letters to distinguish the principal stars of each constellation from each other, and has given some rude maps in which they are employed. Neither Bayer nor Piccolomini at all insist upon their use of letters as an improvement, or even make any prominent allusion to it in their introductions; though, as it happens, the name of either would hardly have been mentioned in our day on account of anything else in their writings. The work of Piccolomini alluded to, was sufficiently well known to be translated into Latin, and published at Basle, (A. D. 1568 or 1588,) so that Bayer may very possibly have seen it.

VI.—Treatises on Natural Theology. There have been a great many attempts to apply geometry to the proof of religious assertions. The last we can find, and one of the most absurd, is " Mathematical principles of Theology, or the Existence of God geometrically demonstrated, &c. by Richard Jack, teacher of Mathematics, London, 1747." Mr. Jack lays down his definitions, one of which is, "the evanescent existence of any being is that point of dura

tion in which its existence terminates or ends;" then proceeds to his axioms, the first of which is, "nothing hath no properties," and another of which is, "no being can exert a power which it does not possess ;"—and finally establishes his point in a hundred and eleven theorems. The following is a specimen.

"THEOREM XXXII. A being cannot act after its existence is terminated.

cr

"Let A be any being: I say it is impossible for the being A to act after its existence is terminated. For let B C represent any portion of time,

A O

+-+ +-+

B D E C

and D the point of duration, when the existence of A is terminated, and D C that part of duration that immediately succeeds the termination of A's existence. It is impossible for A to act in any one point of the duration DC: for if it be possible, let it act in the point E. Then because (Ax. 4) any being exists in all the points of duration in which it acts, therefore the being A will exist in the point of duration E, but its existence terminated in the point of duration D; therefore A will both exist and not exist in the same point of duration E, which is absurd. Therefore, a being cannot act after its existence is terminated; which was to be demonstrated."

We shall notice one more treatise on natural theology, because it is the reverse of the preceding. On account of its shortness, and the practical good sense shown in the method of handling the subject, we shall give it entire. It was published the year after the "House that Jack built."

Gowin Knight, M. B. on Attraction and Repulsion,

3:

London, 1748, p. "The most general truth that oceurs to us, in contemplating the works of the creation is, that there is a Being of infinite wisdom, goodness, and power, the first cause of all things. This is a proposition to which (one would imagine) no one who had ever cast an eye on the works of nature, could deny his assent. But if any such there are, the best advice I can give them is, To look again."

VII.-The differential Thermometer. The late Professor Leslie invented this instrument, we suppose, without being indebted to an old book which the chances were much in favour of his never having seen. It is well known to consist of a curved tube with a bulb at each end; the bottom of the tube, and each side up to a certain height, being filled with spirits of wine; the remainder of each tube and the bulbs being filled with air; thus composing two bodies of air which are prevented from mixing by the interposed spirit. So long as the temperature of the two bulbs of air is the same, the equilibrium is not disturbed; but if the temperature of the air in one bulb be increased, the increased elastic force of the air in that bulb compresses the air in the other bulb by means of the interposed fluid, and the spirit of wine rises in the tube the air of which did not receive accession of heat.

2

In the Collegium experimentale sive curiosum of J. C. Sturm, published at Nuremburg in 1701, the above apparatus is precisely described, and a double-bulbed thermometer drawn, differing only from that of Sir John Leslie in having the two arms of unequal length. The following is the description, (page 49); A and D being the two bulbs, and B and C letters attached to their tubes.