132 



NATURE 



[April io, 1913 



technology has been accumulated at the Deutsches 

 Museum in Munich, and in 1910 the committee 

 of direction decided to publish a series of bio- 

 graphies of men whose work has had a special 

 bearing on these subjects. The first volume to 

 appear deals with the life and work of Georg von 

 Reichenbach,'to whom many advances, not only 

 in the construction of astronomical and surveying 

 instruments, but also in engineering, were due. 

 Born in 1771, his education was carried on not 

 only in school, but also in the workshop with his 

 father, where he showed remarkable mechanical 

 aptitude. At the age of twenty he was sent to 

 England to study mechanical engineering, and in 

 the works of Boulton and Watts in Soho he spent 

 some months working at engine construction. 

 While in England he had not had an opportunity 

 of seeing the works of the leading instrument 

 makers, but availed himself of every opportunity 

 to study this industry also. Ramsden, Troughton, 

 Dollond, Cary and others then supplied the 

 greater part of Europe with instruments of the 

 highest grade, but on his return to Munich he 

 founded workshops for constructing instruments 

 of precision, and for accurately dividing circles. 



In the latter part of the eighteenth century a 

 large amount of surveying was done, and in 1801 

 a base-line 21 ••j km. long was measured near 

 Munich for the systematic survey of Bavaria, 

 so that von Reichenbach found his opportunity. 

 The work of Laplace, Gauss, Bessel and others 

 introduced a great increase in the precision aimed 

 at and attained, and Reichenbach successfully con- 

 structed theodolites for the Bavarian survey 

 with circles up to twelve inches in diameter; he 

 was acquainted with Ramsden 's great 36-in. 

 theodolite which was constructed for General Roy, 

 but apparently preferred the smaller instrument. 



Throughout his work Reichenbach adhered to 

 the vernier in preference to the micrometer micro- 

 scope for astronomical as well as for geodetic 

 instruments on the ground that with the former 

 the portion of the circle was directly measured, 

 while the micrometer measured the enlarged figure 

 of the divisions. The circle of his 12-in. theodo- 

 lite for the Bavarian survey was divided to five 

 minutes and was read by a vernier to four seconds 

 and by estimation to two. The triangulation 

 of northern Bavaria called for the construction of 

 a base-measuring apparatus, and in 1807 von 

 Reichenbach constructed one consisting of iron 

 4-metre bars to be placed almost in contact, the 

 interval being measured by a thin graduated 

 wedge. 



Large astronomical instruments were also 

 constructed for Naples, Genoa, Turin, Mann- 

 heim and elsewhere, and are described as 

 NO. 2267, VOL. 91] 



being among the best of that time. A very 

 fine range of instruments, both astronomical and 

 geodetic, is included in the collections of the 

 Deutsches Museum. But, as Gauss remarked in 

 a letter written to Bessel from Munich, the con- 

 struction of astronomical instruments was not 

 von Reichenbach 's principal occupation. 



Engineering machinery took up more of his 

 time and attention, and in 1808 he constructed 

 water-pressure pumping engines for the salt-works 

 of Riechenhall and Traunstein, and others of 

 improved design were built, and one of these, at 

 Ilsauk, is still working. Iron-bridge construction 

 and steam-engine design and construction also 

 engaged his attention, and in many spheres of 

 activity von Reichenbach showed remarkable 

 originality and brilliant capacity. His family 

 has presented to the Deutsches Museum a large 

 collection of writings, drawings and plans, which 

 have been extensively utilised in the present 

 monograph, wherein Dr. W. von Dyck has pro- 

 duced not only a highly interesting account of a 

 man of exceptional ability and resource, but has also 

 rendered available a large collection of valuable 

 and important documents relating to the construc- 

 tion of instruments of precision and of machinery, 

 and some of these are reproduced in the plates 

 which illustrate the monograph. 



PURE AND APPLIED CHEMISTRY. 



(1) Chemistry of the Oil Industries. By J. E. 

 Southcombe. Pp. ix + 204. (London : Con- 

 stable and Company, Ltd., 1913.) Price fs. 6d. 



(2) Achievements of Chemical Science. By Dr. 

 J. C. Philip. Pp. vii + 217. (London: 

 Macmillan and Co., Ltd., 1913.) Price is. 6d. 



(3) Le Celluloid et ses Succedanes. By W. 

 Main. Pp. 162. (Paris : Gauthier-Villars, 

 1913.) Price 2.50 fr. 



(4) Ausfiihring qualitativer Analysen. By Wil- 

 helm Bilz. Pp. xi+139. (Leipzig: Akade- 

 mische Verlagsgesellschaft m.t>.H., 1913-) 



(1) ' I ""HIS work fulfils in a very satisfactory 

 1_ manner the author's attempt "to fill a 

 gap between the elementary text-books of organic 

 chemistry and the numerous technical treatises 

 and monographs of a highly specialised char- 

 acter." The opening chapter on the chemistry 

 of the hydrocarbons and their derivatives will 

 facilitate the reading of later sections by those 

 not very conversant with organic chemistry, but, 

 in the interest of these readers, exception must be 

 taken to the use of the expression "rests," in 

 reference to unsaturated groups or complexes 

 (pp. 14-15). The adoption of this Germanism is 

 quite unwarranted, inasmuch as the idea can 



