88 



KNOWLEDGE 



[Apbil 1, 1896. 



from the preceding. In the triangle, included within these 

 three poiuts, eighty-three stars were shown on the 

 original negative. Taming now to Fig. 2, we find the two 

 stars, one at the intersection of lines 20 and 37, the other on 

 line 25, and midway between lines 37 and 38, and the clitster 

 near the intersection of lines 21 and 41. Within this 

 triangle the original plate, taken with the star camera, 

 showed no fewer than one thousand one hundred and sist)-- 

 six stars. And this proportion — fourteen times as many 

 — Mr. Kussell found to be " a fair index of the greater star- 

 grasping power of the long star camera." In the smaller 

 pictures stars are lost, both by want of that sharp definition 

 which the telescope of longer focus gives, and by the 

 images of neighbouring stars being run together, which 

 are distinctly separated on the greater scale of the star 

 camera photograph. An appearance of nebulosity which 

 has no real existence may, therefore, be created in places 

 on the small scale plates, and in this particalar instance 

 the " face " to which Mr. Einyard called attention in the 

 Lick photograph can no longer be saen in the larger scale 

 plate now before us. " My own experience," Mr. Kaasell 

 writes in this connection, " leads ma to think that one is 

 apt to ba misled by forcing the development of astro- 

 nomical photographs of the Milky Way. I have found, 

 for instance, that what I took to be nebula in one of my 

 short camera pictures turned out to ba simply stars 

 when taken with the long camera, just as in the case 

 above referred to." 



Yet the curves and lines of stars are still to be seen, and 

 the dark " lanes" and rifts. In these two photographs the 

 rifts tend to ba winding and irrejular, though Fig. 1 shows 

 at least one uainistakable "lina" as straight as it could 

 possibly be. Tnese configurations, then, are no mere 

 delusive eS'acts of the necessary imperfections of small-scale 

 photographs, but have an actual existence. 



The field for the short focus camera in astrographic 

 work is two-fold : the detection of faint extended nebulous 

 matter, and the rendering of broid aspects of stellar 

 grouping. For the accurate presentation of details, we 

 must turn to telescopes of considerable focal length. 



The two photographs show, beside the stars, the imprint 

 of the lines of the standard reseiu, used on all the plates of 

 the Internitional Chirt, bjth for convenience in measuring 

 the plates and for the detection of accidental distortion of 

 the film. 



Notices of Booifes, 



From tJie Greeks to Darwin, By Prof. Henry Fairfield 

 Osborn, So.D. Pp. 251. (Mtcmillan & Co.) It is worth 

 remembarmg that two thousand years ago Aristotle had a 

 general conception of the origin of higher forms of life 

 from lower, and that he considered and rejected the theory 

 of the survival of the fittest as an explanation of the 

 evolution of adaptive structures. Evolution has, indeed, 

 only reached its present fulness by slow additions from 

 the days of the Ionian school ; in other words, the theory 

 has itself been evolved. In the philosophic volume which 

 Prof. Osborn has presented to the scientific world, the 

 story of the development of the evolution idea is traced 

 from the earliest times. He distinguishes four specia 

 stages in this progression. Between 6i0 b.c. and 1600 a.d. 

 the world saw the rise, decline, revival, and final decline 

 of Greek natural history and Greek conception of evolution. 

 In the seventeenth and eighteenth centuries moJeru 

 evolution, as part of a natural order of the uaivarse, had its 

 beginning ; tnen cxme the perioi of midera inductive 

 evoiutioa, with which are associated the names of Buffon 



and St. Hilaire, of Erasmus, Darwin, Goethe, Treviranus 

 and Lamarck ; and finally we have the fourth period 

 commenced by the publication of Darwin and Wallace's 

 observations — a period which is marked off from the others 

 so abruptly that it may well be regarded as the beginning 

 of quite a new era, for since 1858 more works upon 

 evolution have appeared each year than in all the centuries 

 previous. The '• tyranny of space" prevents our giving a 

 critical notice of Prof. Osborn's scholarly work. We can 

 only say that the author appears to have carefully and 

 impartially considered the truths and speculations that 

 clustered round the doctrine of evolution in the twenty-four 

 centuries between Thales and Darwin. No student of 

 evolution should be content until he is familiar with this 

 history of the theory's struggle for existence. 



What is Heat ? By Frederick Hovenden, F.L.S., F.G.S., 

 F.E.M.S. Pp. 350. (W. B. Whittingham & Co.) Mr. 

 Hovenden poses as a Daniel come to judgment. He essays 

 to correct the conclusions of such investigators as Maxwell, 

 Clausius, Joule, and L )rd Kelvin, with regard to the 

 kinetic theory of matter, and after proving to his own 

 satisfaction that the physicist generally " has got much 

 beyond his depth," he states a new hypothesis in a series 

 of twenty-three articles. Here is one of these confessions 

 of faith : — " When ether is uninfluenced by external forces, 

 it rises from the surface of the earth or anti-gravitates ; 

 and when atoms or molecules absorb this fluid, they 

 increase in volume in the ratio to the quantity of this fluid 

 absorbed, and they become in that ratio also specifically 

 lighter. Therefore atoms and molecules ai-e not constant 

 in dimensions." Merely to state Mr. Hovenden's ideas 

 would take up many of our columns, and as anything we 

 might say about them would assuredly be accepted as 

 commendation, it is judicious to refrain from traversing 

 his arguments. The many experiments he has made 

 indicate that he is a man of energy and ingenuity ; but 

 the conclusions drawn from the experiments are sufficient 

 to prove, to every competetent judge, that his perspicacity 

 is as faulty as his knowledge of molecular physics is 

 deficient. 



A Handbook to the Order Lepidoptera. By W. F. Kirby, 

 F.L.S., F.E.S. Part I., Butterflies. Vol. I., pp. 215. 

 (London : W. H. Allen & Co., Limited, 1894.) This la 

 another volume in the " Naturalist's Library," edited by 

 Dr. Bowdler Sharpe. Like its companions, it is readable, 

 instructive, and well illustrated, and Mr. Kirby's name is 

 a sufficient guarantee for accuracy and completeness of 

 work in the present state of knowledge. The volume 

 deals with the great family Nymphalidie taken in their 

 broad sense, and the second volume will be devoted to the 

 remaining families, so that the two will form a complete 

 work on butterflies. The young collector and the serious 

 student of entomology should certainly add the volumes to 

 their libraries. They will thus possess an excellent work, 

 not only on British butterflies, but on the butterflies of the 

 world. 



Elements of Astronomy. By George W. Parker, M.A. 

 Pp.232. (London: Longman, Green & Co.) Judging from 

 this production, we should say that the author has only 

 a limited acquaintance with astronomy. It may appear a 

 mere cavil to complain that the work lacks originality, for 

 the mathematical principles involved in developing the 

 theory of celestial motions are the same yesterday as 

 to-day. Nevertheless, when a work such as Hersohel'a 

 " Outlines " or Young's " General Astronomy " appears, 

 something new and attractive in the mode of presentation 

 is apparent to every competent critic. The fact is, iAx. 

 Parker has fashioned his work according to the require- 



