REVIEW.

Globe, Volume IX, Issue 1347, 8 June 1878, Page 3

REVIEW.

STAR-GAZING* [from the press.] Mr Michael Proctor and Mr Norman Lockyer have done a great deal towards popularising the study and the results of astronomy. The writings of the former are many and varied. They usually appear first in a serial form, and are afterwards collected and published in volumes. Mr Proctor deals chiefly with the history and the results of astronomical discovery. Mr Lockyer’s forte lies rather in the ways and means by which these results have been obtained. That he can expound the facts and principles of the science is proved by his valuable little book, “The Primer of Astronomy.” But he rightly prefers to throw his strength into what may be called instrumental astronomy. It is through the invention and the improvement of mechanical means that such wonderful and accurate things have been achieved. This new book is got up in a style worthy of the theme and the writer. The five hundred pages are beautifully printed in easily read type. There are also as many as 200 illustrations, one of them, the frontispiece, being a photograph of Mr R. S. Newall’s magnificent telescope, a 25-inch refractor. Whether dealing with the observation or with the chemistry of the stellar worlds, the reader, by means of these aids, is able to understand every portion of the subject. The matter of the book was delivered as a course of six lectures at the Royal Institution. These lectures were taken down in short-hand at the time, and they arc now revised by the author and published in this splendid volume. The writer traverses the usual ground in sketching the progress of the science, but with the distinct and single object of enumerating and describing the various instruments used by the old observers. The first book is devoted to the pre-telescopic age. Tycho Brahe marks the transition to a more glorious era in astronomical discovery, he being the last who used instruments without the telescope. Considering how rude and simple the mechanical aids were, we may well wonder at the results achieved before and by the distinguished Danish observer. The invention, the successive improvements, both in range and in mounting of the telescope, are then described. The illuminating power of this instrument is thus made perfectly clear. “ If one takes the pupil of an ordinary eye to be something like the fifth of an inch in diameter, wnich in some cases is an extreme estimate, wo shall And that ita area would be roughly about one-thirtieth of an inch. If we take Lord Rosse’s speculum of six feet in diameter, the area will be something like 4000 inches ; and if wo multiply the two together we shall find, if wo lose no light, we should got 120,000 times more light from Lord Rosso’s telescope than we do from our unaided eye, everything supposed perfect” (p. 159). One great difficulty hitherto has been to get object glasses, which shall bo at once large and pure. Common glass can be ground smooth enough for a speculum, but to grind it into lenses bullied for a long time both the astronomer and the optician. To Holland belongs the credit of putting later improvers on the right track by bis employment of flint instead of crown glass for the purpose. Two inches in diameter was thought by Holland to be something wonderful. But this is how progress has been made. In the year 1820 we hear of a piece of flint glass 6in. in diameter, and in 1859 Mr Simms reported one of 73-in. But even then they were doing better things in Switzerland. M. Guinand produced achromatics of 9in. Afterwards Merz, his successor, obtained lenses of the then unprecedented diameter of 15in. “ Now wo have in nart turned the tables, and Mr Chance, of Birmingham, owing to the introduction of foreign talent, has since constructed discs of glass of a workable diameter of 25im, for Mr Newall’s telescope, and for the American Government lie has completed the large discs used ja constructing the refractor of 2tiin. diameter for the Observatory at Washington (the Americans are never content till they can go an inch beyond their rivals). Now a Frenchman has eclipsed us. M. Feil, of Paris, a descendant of the celebrated Guinand, has made one of nearly 28-in. diameter for the Austrian Government.” Mr Newnll has done for America whqt Lord Rosso did for Britain — provided, at a cost of many thousand pounds, the best teh scope at present in existence. It is a refractor, and its erection and employ - rrent will have a most important bearing on the astronomy of the future. In the latter portion of the book, Mr Lock° yer is dealing with astronomical physics chemistry and photography. In each of these domains he is quite at home, and in any of them he is easily first. Mr Lockyer was the first to act on the suggestion of Hr. Jansson, and employ photography in * Star-Gazing: Past and Present. By J. Norman Lockyer, F.K.S. Macmiliau and Co., 1878. (Wood and Co., High street, Christchurch.)

tho late transit of Venus. Photography is now made use of in many astronomical operations, and it is already bringing about the most startling result. By its means pictures of the different celestial bodies have been obtained of surpassing excellence. “We are now not only able to register and determine the appearance of tho moon and planets, but day by day, or hour by hour, with assistance of a driving clock, we can photograph a large portion of tho solar spectrum ; and not only so, but the spectrum of the different portions of the sun, nay, even the prominences, have been photographed in the same manner; while more recently still Drs. Huggins and Draper have succeeded in photographing tho spectrum of some of the stars.” Another now book by MrLockyer —“ Studies in Spectrum Analysis,” has just reached us, some account of which will in due time be given.