Aprils, 1881] 



NA TURE 



535 



In a room on the floor above there is a special exhibi- 

 tion of a large number of photographs, which is being 

 constantly increased by new additions. They consist 

 of photographs of all the ancient instruments copied 

 from engravings of the period ; and all the foreign instru- 

 ments in present use, taken from nature. There are also 

 drawings representing the principal observatories in the 

 world. 



Such is the commencement of the astronomical museum 

 of the Paris Observatory. It will be completed by organ- 

 ising a second circular room resembling that which we 

 have just rapidly passed under review. This new room 

 will be adorned with portraits of the most illustrious of 

 foreign astronomers : — Newton, Galileo, Tycho-Brahe, 

 Kepler, Copernicus, Herschel, Bradley, and others. It 

 will also contain a special exhibition of large astronomical 

 instruments ; notably a quadrant of Lalande's, a sextant 

 of Lacaille's, a quadrant of Langlois' which was used by 

 the North Pole Committee, and a meridian telescope of 

 Delambre. 



It would be useful to bring together in the Paris Ob- 

 servatory those instruments which are scattered here and 

 there in various other national institutions, so as to com- 

 plete a collection already so rich in valuable objects. The 

 directors will also gratefully accept of any bequests that 

 may be addressed to them from private individuals, as 

 was done by Mme. Laugier with reference to the instru- 

 ments of Arago and Delambre which she had in her 

 possession. 



After our survey of the new Astronomical Museum, it 

 now remains to say a few words regarding the extension 

 of the observatory, which is about to be made by annexing 

 the ground on the Boulevard Arago (Fig. i). This waste 

 land contains a superficies of at least gooo metres, and 

 when the ditch which at present divides it from the Ob- 

 servatory garden is filled up, it will be united to the rest 

 of the institution without any separation. C)n these 

 grounds will be erected the great 75 m. telescope, the 

 arrangements for which are already well advanced ; also 

 the equatorial presented by M. Bischoffsheim, the circle 

 of Fortin, which long rendered excellent service, and was 

 dismounted in 1862 to niake room for the the great 

 meridian-circle, and several instruments for the special 

 use of the pupils. 



The plan which we give above (Fig. i), from official 

 documents, shows what the Paris Observatory will be as 

 a whole when the projected improvements are completed. 



We regret that the works are being so slowly carried 

 on, notwithstanding the praiseworthy energy evinced by 

 the directors of the Observatory. A ditch to be filled in, 

 a garden to be laid out, a few buildings to be erected, all 

 amount to but very little. But before the masons cut a 

 stone or the gardeners trace an alley there is a path to be 

 traversed which is not exactly the shortest or quickest, 

 viz. that of administrative and official routine. 



ACHILLE DELES SE 



WE regret to have to record the death of this eminent 

 geologist, which took place, after a long illness, on 

 March 24. Delesse was born at Metz, and was educated 

 at the lyceum of that town, afterwards proceeding, at 

 the age of twenty, to the 6cole Polytechnique at Paris. 

 He was a diligent and successful student, and in 1839 

 took his degree as a mining engineer. He then travelled 

 for some time through his own country, in Germany, 

 Poland, and the British Islands, and in 1845 was ap- 

 pointed Professor of Geology and Mineralogy at Besan- 

 (jon, where he also practised as a mining engineer. It 

 was during his residence here that he wrote his " Notice 

 sur les Characteres de I'Arkose dans les Vosges," and 

 his " Mdmoire sur la Constitution mindralogique et chi- 

 mique des Roches de Vosges," both of which works 

 appeared in 1847. After a stay of five years at Besangon 



Delesse returned to Paris, where he was employed as a 

 mining engineer, and was especially engaged in superin- 

 tending the quarrying operations about the city for nearly 

 eighteen years. In 1S55 he prepared the report on 

 building materials in connection with the Exposition 

 Universelle of that year in Paris. In 1864 he was nomin- 

 ated Professor of Agriculture, Drainage, and Irrigation 

 in the Ecole des Mines. Delesse's earliest re^errches 

 were directed to pure mineralogy, and he paid great 

 attention to the subjects of pseudomorphs and the asso- 

 ciation of minerals, and this led him to study the ques- 

 tion of the metamorphism of rocks. The outcome of this 

 perior' -•' study was his well-known work, " Recherches 

 sur rOri_,'ine des Roches," published in 1S65, in which he 

 argued ably and forcibly in favour of the view that crys- 

 talline rocks owe many of their characters to che action 

 of superheated water, and are not produced by simple 

 dry fusion. This important work of Delesse has exercised 

 a marked and very beneficial influence on the progress of 

 petrographical science, and its originality and value were 

 at once recognised by the most advanced thin' ers of 

 the time. Already in 1858 Delesse had published two 

 of his valuable maps, namely, the " Carte g^ologique 

 soutteraine de la Ville de Paris" and the " Carte hydro- 

 logique de la Ville de Paris," and his subsequent studies 

 came to be especially directed into the channels of inquiry 

 which were associated with the professorship that he had 

 created and so ably filled. In 186S appeared his work 

 on the Rainfall of France, and other memoirs treating of 

 the agricultural bearings of geology were produced about 

 the same period. 



The war of 1870 caused an interruption in the scientific 

 labours of Delesse, and we find him at this period super- 

 intending the construction of cartridges in the depart- 

 ments- But in 1878 he was appointed an Inspector- 

 General of Mines, and the south-east of France was 

 assigned to him as his district. During the last twenty 

 years Delesse has issued, in conjunction with MM. Langel 

 and de Lapparent, a series of annual volumes entitled 

 " Revue de Gdologie," a work of such value that we regret 

 to hear that it is to be discontinued in the future. Delesse 

 received many honours in recognition of his valuable 

 labours. He was an officer of the Legion of Honour, 

 and filled the post of President of the Geological Society 

 of France. As long ago as 1859 he was elected a 

 Foreign Member of our own Geological Society. He 

 was also for two years President of the French Geological 

 Society, and he' occupied the chair during the Inter- 

 national Congress of that Society in 187;. In 1879 

 Delesse was elected a Member of the Academy of 

 Sciences. In Delesse France has lost one of her most 

 distinguished and widely-known scientific men. 



PROFESSOR HELMHOLTrS FARADAY 



LECTURE 



ON Tuesday evening Prof. Helmholtz gave the Faraday 

 Lecture of the Chemical Society at the Royal Insti- 

 tution. We have so recently (Nature, vol. xv. p. 389) 

 given a full account of the life and work of the eminent 

 German worker in various departments of science, that it 

 is unnecessary to go over the ground again. A very fair 

 estimate of his position was given in a leading article in 

 the Times of Saturday last ; and we are glad to notice 

 that the leading journal now is glad to draw attention 

 to men of science whose work is deserving of pubhc 

 notice. The University of Cambridge did itself the 

 honour of conferring upon Prof. Helmholtz the degree 

 of LL.D. on Thursday last, on which occasion the public 

 orator, Mr. Sandys, made the following elegant and appro- 

 priate speech : — 



" Dignissime domine, domine Procancellarie, et tota 

 Academia : 



" Singularum quidem scientiarum terminos protulisse, 



