August 17, isjt!. 



SCIENCE. 



•203 



It is cvidpiit, liowcvpr, tliat tlie nutlior docs 

 not fully firasp all the piiiu-ipk's involved in 

 these macliiiK's, or he would hardly have spoken 

 so disparagingly of the 'spring-governor* of 

 Bond, whieh is unquestionably, when properly 

 adjusted, one of the most perfect of all. In 

 so full a treatment of the subject, one would 

 naturally expect to linil some notice of tlie 

 ingenious arrangement by which the clock- 

 work of the Dun Kcht equatorial is brought 

 under tlie electric control of the standard time- 

 piece; but it is missing, though Gruhb's less 

 perfect apparatus for the same purpose is fully 

 described. 



The fifth chapter, dealing with micrometers, 

 calls for no special notice, beyond the remark 

 that it strikes one as a curious classification 

 which treats of chronogrnplts in this connec- 

 tion. 



The sixth chapter is a short one. describing 

 the different forms of helioscopes and solar eye- 

 pieces, and the most convenient arrangements 

 for making drawings of sun-spots and deter- 

 mining their position. 



The seventh chapter is intended to bo a full 

 and elaborate descrijition of the different forms 

 of astronomical spectroscopes, with their ac- 

 cessories. It does describe and figure a great 

 man}- ; but there are several mistakes (as, 

 for instance, on p. ().')6, where the temporary 

 device which Professor Young employed in 

 observing the eclipse of 1809 is said to have 

 been used with a heliostat, and is spoken 

 of as if it were now used at Princeton), and 

 there is the capital omission of failing even to 

 mention the use of diffraction-gratings in spec- 

 troscopic work. It strikes one as very sur- 

 prising th.1t the author should not have learned 

 th.at for solar observations the grating has 

 almost entirely supplanted the jirism in many 

 if not most observatories. The remarkable 

 apparatus of Thollon is alluded to, but not 

 described with any fulness. 



The remaining chapters of the book treat of 

 a))paratus for celestial ))iiotograi)liy, photom- 

 etry, and the measure of solar radiation. 



Similar remarks apply to these as to the pre- 

 ceding. There are many excellent descriptions 

 and illustrations, many important omissions, 

 and a few mistakes. We call special attention 

 to the fine representation of the most ingen- 

 ious mounting — devised by Hansen, and con- 

 structeil by Hepsold — for the i)liotoheliographs 

 employed b^- the German transit of Vemis 

 parties, — a contrivance which we have never 

 seen described elsewhere. But in the chap- 

 ter on photogra])hy, neither the name of II. 

 Draper nor of Common appears ; and Ruther- 



ffird's photographs of the spectrum are said 

 (on p. K'2~) to have been made with an appara- 

 tus he never even saw. the instiutneut figured 

 being a spectroscope which was i:sed at Dart- 

 mouth college in attempting to photograph the 

 solar prominences, while the description given 

 is incorrect in several particulars. In the chap- 

 ter on the measurement of radintion the ap- 

 paratus of Pouillet and Secclii appears, but 

 nothing later, — none of the instnnnents of 

 ^'iolleorCrova, and, of course, not the bolom- 

 eter of Langley. The chapter on photome- 

 ters is much better brought up to date. 



On the whole, the book is rather a provok- 

 ing one. There is a great deal in it of real 

 value, collected from various more or less in- 

 accessible sources, and very neatly presented ; 

 but the lacunae are serious, and a few detected 

 mistakes leave a sense of insecurity .as to accu- 

 rac}- in other details. 



BURNHAM'S LIMESTONES AND MAR- 

 BLES. 



IThlnr;/ and u.ien of Hmmtones and marhles. With 

 fcrty-eight chromolithographs, liy S. M P>rn.\- 

 liAM. Boston, 6'. E. Casino 5" Co., 18S3. 15 

 -1- 392 p. 8°. 



The separate cryst.ils of our rocks, when 

 they lend themselves to decoration in the form 

 of gems, afford a capital opportunity for the 

 book-maker. .Superstition, tradition, a host of 

 human activities, have gathered about them, 

 that, in the hands of writers of skill, have 

 been worked into very readable books. But, 

 when the author of ' Limestones and marbles' 

 tries to take something of the same book- 

 maker's w.ny with the coarser though still 

 beautiful marbles, he leaves the field of 

 thoroughly humanized things, and finds himself 

 in a dreary sea of unrelated facts. A writer 

 thoroughly conversant with the architectural 

 history of building and ornamental stones 

 could probably give us a book which would, 

 from its connection with the most economic 

 of the fine arts, be very readable. A skilled 

 lithologist who would fm-nish us a careful dis- 

 cussion of the nature of those changes which 

 give beauty, strength, and endurance to rocks, 

 would thereliy furnish us with a needed ess.iy ; 

 but in this book we have 7io trace- of these 

 capacities, but only the ordinary patience of 

 the devoted compiler. 



As a piece of unwearied compilation, unen- 

 livened with any higher quality, this is a very 

 remarkable book. In the list of limestones 

 of the United States we have evidence of a 

 most universal but most uncritical ransacking 



