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vented another, of a more complicated kind. But although several extremely ingenious calculating machines have been constructed since that period, the only machine of the kind in Paris was that exhibited by C. Thomas, of Colmar, which multiplies 8 figures by 8 in eighteen seconds; divides 16 figures by 8 in twenty-four seconds; and extracts the square root of 16 figures in ninety seconds. The price of this machine was £20. It is to be regretted that a specimen of the extremely beautiful calculating machine invented by the Messrs. Scheutz, of Stockholm, was not exhibited. One of these machines is employed in calculating a new life table in the Registrar General's office in London, and simultaneously prints the results.

It would greatly exceed our limits to even briefly notice the numerous objects falling under the head of miscellaneous philosophical instruments. A few, however, are too important to be omitted. Among them may be classed Lissajous' and Desain's apparatus for representing acoustic vibrations optically and graphically, exhibited by the maker, M. Koenig. This apparatus is the most perfect that has been devised for demonstrating the various combinations of rapid vibratory movements. Many other beautiful and novel acoustical instruments were exhibited by M. Koenig, who has been for many years engaged with great success in investigating the laws of sound.

The collection of spectacles by continental makers was extremely large; but as the eminent British makers of these useful articles did not exhibit, no comparison can be instituted between them and the former. How much machinery has done to reduce the price of spectacles is apparent by the fact that the house of Morey, Baillet, and Co. manufacture excellent spectacles, in good steel frames, which are sold at 2s. 6d. the dozen pair. In nearly all the spectacles exhibited provision has been made to enable the axis of each eye to coincide with the central spot of the lens, without which arrangement spectacles must be always defective.

In the department of philosophical instruments, the Paris Exhibition contained a great variety of models of machines, drawings for teaching the physical, natural, and musical sciences, anatomical preparations, etc. With scarcely an exception, all these were contributed by continental countries, the governments of which are far more disposed to afford facilities for technological instruction than that of our own. The objects of this nature exhibited by France, Belgium, Prussia, Italy, and Russia, were admirably adapted for the above purpose. There was a very interesting exhibition in the department of anatomy, by Dr. Brunetti, of Padua, who has discovered a process by which, in thirty hours, he can

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preserve the human and other bodies. The preparations are life-size, and so little changed by the process, that they can be used for anatomical purposes, nor are they affected by time or insects. A committee of the Paris Academy of Sciences has been appointed to examine and report on Dr. Brunetti's invention, with the view of purchasing the secret of his process, should it be found to be valuable.

In conclusion, we may remark, that although no just comparison can be made between the merits of foreign philosophical instrument makers and those of our own country, in consequence of the absence from the Exhibition of many of our most eminent makers, there is no doubt that in this department, as well as in many others, continental nations show great progress. We have, indeed, only to examine the foreign mechanical products to be made aware that the excellent and comprehensive practical education afforded throughout the greater part of the continent, and especially in Prussia, has already borne valuable fruit; and if we desire to keep up in the race of progress, we must be at more pains to disseminate technological education among skilled artisans.

The philosophical instruments lately exhibited in Paris were not, it is true, remarkable for any great novelty, but they were highly remarkable for their general excellence; and this was often to be found in instruments made in countries which a few years ago did not produce an ordinary barometer. It was also a very noticeable feature that the foreign instruments are much more moderate in price than the English, which is principally due to the lower rate of wages paid to

continental workmen.

To the philanthropist who desires to see the advance of mankind, this progress is extremely gratifying. "The introduction of noble inventions," says Lord Bacon, "seems to hold by far the most exalted place among all human actions. This," he adds, "was the judgment of the ancients, who accorded divine honours to inventors." And by the improvement of existing, and construction of new philosophical instruments, we have every reason to believe that the prosperity and happiness of the great family of mankind is largely advanced.

LUNAR SKETCHES.-TRANSITS OF JUPITER'S SATELLITES.-OCCULTATIONS.

BY THE REV. T. W. WEBB, A.M., F.R.A.S.

IN our last number we gave the commencement of a few original rough sketches of the lunar surface in the neighbourhood of Eratosthenes and Copernicus, as a small contribution to the materials which in great measure yet remain to be collected for future comparison and study. We now propose to continue our remarks upon the same interesting region.

Eratosthenes.-The following notices may be referred to, concerning this crater.

1856. Jan. 15. 3,7-inch achrom. "One-third of ring faintly enlightened beyond terminator, and just connected with it by a dimly lighted ascent," showing that the ground in the neighbourhood of this great eruption had been upheaved like that round Copernicus, though in a much less conspicuous degree.1861. April 18. 54-in. achrom. Terminator through Tycho (48) and Fontenelle (N. of Plato, 38). "The wall a grand sight in itself. Its N.W., W., and S. slopes to a considerable distance are most curiously roughened with small hillocks and ridges, whose general direction is concentric with the wall, and whose appearance bespeaks a former semi-fluid condition," as, perhaps it might have been added, their arrangement would rather suggest the ejection of blocks than the flow of lava. Such ideas, however, can only acquire weight from extended observation. That the surface hues in and around it are of a decided character appears from the following notices. 1864. Aug. 13. 5-in. achr. "The wall still casts a penumbra on each side, yet the interior begins to show local colour." Aug. 15. (1d. 16h. before Full.) "Penumbra gone; a strange mixture of light and duskiness on its site." How these shadowings are arranged will appear, to some slight degree, from the two following entries, which I quote just as they stand, having given no further attention to the region, and being at present unable to examine how far they admit of being reconciled. 1864. July 22. (3d. 17h. after Full.) 5-in. achr. "Eratosthenes has its E. side filled with a dark lake, or rather, two such spots. joined by a narrower neck: a small dusky spot lies also at the W. foot of the central hill." 1867. Nov. 8. (3d. before Full.) 9-in. silvered "With " mirror. "Eratosthenes now all in local colour; from point of junction of Apennines round the E. semicircle, the outside glacis of wall shows a curious dark grey border. This is penetrated in two places by the streaks of Copernicus, which extend perhaps (but qu?) across Eratosthenes

itself. Curious as to chronological sequence." It is just possible, however, that some process affecting the reflective power of the surface may at this time be working here; for B. and M. say that this crater is "in Full Moon not very distinct: we only see a very undefined faint light spot in a vicinity almost equally luminous." No mention is made of any darker portions, or of their being so situated as to indicate the position of the ring, and the description certainly does not tally well with present appearances. This is a peculiarly suitable spot for examining the question whether the Full Moon markings are unchangeable. Fixity, of course, if established by a long course of observation here, or anywhere else, would be no argument for its universal prevalence, since a state of quiescence in this respect might be attained at very different epochs in different regions; but should the reverse be clearly ascertained in a single well-marked, even though minute, case, it need not be mentioned that one distinct, incontrovertible affirmative weighs down any number of negative instances, and merely throws back the date of their changes to a pre-historic period. Sketches at the telescope, in lamp-black, Indian ink, or sepia, if really careful and trustworthy, would be very valuable, and in some hands made with much facility. There is this great convenience attending them-that the groundmarkings they represent are much less fugitive than the actual shadows indicating the relief of the surface, and that many more opportunities are afforded in each succeeding lunation for the production of such designs, than of delineations containing ordinary effects of light and shade. And hence, by the way, as regards that great desideratum, a good map of the Full Moon, much more might be effected in a corresponding time than in the case of the details of actual relief. Even a single observer, possessed at once of accuracy of eye and artistic training of hand, might make a great advance in the right direction. To such an one (but more than one, we trust, may be found) the experience of the Astronomer Royal for Scotland (Piazzi Smyth), himself eminent alike as astronomer and artist, may be acceptable. In sketching the Mare Crisium, at the request of the former Lunar Committee of the British Association, he found oil colours much preferable to water for producing a likeness under the required conditions. It need scarcely be added that a large scale would be required to follow his example with success. But to return to our immediate subject:

Sinus Estuum.-1864. Dec. 6. 54-in. achr. "The entrance of this dark plain is magnificent, and the curved banks lying obliquely over one another, but with a general parallelism to the mountain boundary, look like the rolling waves of some

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viscous material, agitated just before consolidation." remarkable appearance here referred to is not confined to this region. I have traced it in others of the so-called lunar seas : in the M. Nubium (M), the M. Humorum (N), the M. Nectaris (O), and near the E. shores of the M. Serenitatis (E); further search will probably detect it in other situations; and it is probably one of those significant features which deserve peculiar attention in any speculation as to the probable origin of existing configurations. Very imperfect at present such speculations must necessarily be; and whether they may ever assume the proportion of a consistent theory will depend first on diligence of examination, and next on the care and impartiality exercised in dealing with the materials of thought. At present they are but guesses and inquiries, worthy of being recorded only so long as they make no further pretension.

Stadius. The curious discovery of a number of minute craters within this slight enclosure was made by Dr. Dobie, of Chester, with a 54-in. object-glass in the summer of 1863. His obliging communication of it to myself led me to wish for an examination of the region, which I was unable to accomplish for a considerable time; the illumination suitable for such minutiæ being always transient, and the air not frequently sufficiently steady. However, 1865, Jan. 6, when the terminator was passing through the E. side of Reinhold (31) and Bullialdus (60), and definition, with haze and a cold N.W. breeze, was fine, but rippled over, and very unsteady, my 5-in. achr. enabled me to make out 10 or 12 minute pits, similar to those in the crater-chains of Copernicus, but smaller, and without distinct rings; they were chiefly in S. and W., and none, I thought, in the centre. I detected them again 1866, Feb. 23, the terminator having passed beyond Plato (38) and Tycho (48) by the amount of their own diameters; and I have since seen them with my beautifully defining 9-in. silvered mirror, but not under the favourable circumstances which they require. May we imagine that these are of modern date? The large maps of B. and M. and Lohrmann contain only one small crater in the S.W. part of the floor of Stadius, a crater which I think I have seen pre-eminent among the rest; but the others might easily have escaped the small aperture of B. and M., and Lohrmann's Sections and letterpress unfortunately do not extend so far: we must, therefore, suspend our opinion, and allow the probability to be decided by less ambiguous evidence elsewhere. In one respect this region is worthy of attention on the part of those who have a clear optical command of it: its circumscribed nature enables the little included cones to be counted and drawn with greater certainty than might be the case in a less definite area. We proceed now to the

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