464 



NATURE 



[September 15, 1892 



and contains information upon all sorts of subjects, from a 

 list of abbreviations usually employed in writing, to a de- 

 scription of the rare metal zirconium. Between these 

 two articles we find notices of the methods of brewing, 

 and the proper way of laying bricks and ventilating 

 houses, the nature and treatment of broken wind in 

 horses, the composition of digestive, aperient, and tonic 

 pills, the practice of photography, the nature of infective 

 diseases in man and beast, the destruction of caterpillars 

 in plants, the best kind of clothes to wear, and the method 

 of taking grease spots out of clothing. From these 

 samples of the contents it will be seen that the book is 

 really a most extraordinary work of reference and one 

 which is not likely to lie idle on the shelves, but to be more 

 or less in constant use. The work of revision has evi- 

 dently been carefully done, and must have been one of no 

 small labour, as it has been brought well up to date and 

 many articles must be entirely new. The great practical 

 utility of the work is shown by the large circulation it has 

 enjoyed for many years, and the editor has done his best 

 to maintain the well-deserved reputation of the book. 



Traitc Encyclop'ediqiie de Photographie. First Supple- 

 ment A. Par Charles Fabre. (Gauthier-Villars et 

 Fils, 1892.) 

 Many of our readers are already thoroughly acquainted 

 with this excellent treatise which we owe to M. Fabre. 

 In the present volume we have the first of the series of 

 supplements which will be issued in order to keep the 

 book well up to date. The range of progress here shown 

 is that accomplished during the years 1889-92. The same 

 arrangement as to numbering the paragraphs is still 

 presented, so that it will be quite easy for those having 

 the original volumes to refer to any section in this sup- 

 plement. 



The matter which is chiefly treated of here refers to the 

 various properties and kinds of lenses and to their com- 

 binations : thus some of the most important headings 

 that have been considerably developed may be stated as 

 follows : — Methods of measuring focal distances, Martin's 

 objectives, simple objectives, calculation of objectives, 

 rapid euryscopes, Zeiss' objectives, &c. Many other new 

 discoveries, such as Lippmann's photography in colours, 

 have also received attention. 



With these supplements this encyclopedia will be found 

 to be greatly enhanced in value, for at the present day 

 photography is undergoing many and rapid changes the 

 recording of which in this form is no light task. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part oj Nature, 

 No notice is taken of anonymous communications. ] 



The Mustakh Exploration. 

 Mr. Conway's march from our newly acquired district of 

 Hunza into Baltistan (reported in the Times), up the Hisper 

 glacier on one side and down the Biafo on the other to 

 Askolay, is a splendid feat to have accomplished, a memorable 

 achievement, and his account of it will be something to look 

 forward to on his return to England. The total length of these 

 two glaciers is certainly something between sixty and seventy 

 miles measured upon the map, and over this distance the glacial 

 forces in action are on the grandest scale. The view obtained 

 of the Hisper glacier from the two points we ascended on either 

 side of the Nushik La is hardly to be described, from thence the 

 end of the Hisper glacier is not defined, and could 'only be 

 indicated from the run of the spurs on the north side of the 

 valley, and what information the guides could give. This made 

 the total length sixty-four miles. By traversing this length of 

 the two glaciers Mr. Conway has been able to get into ground 



NO. I 194, VOL. 46] 



never before visited, viz. , that great ice field on the main range 

 of the Mustakh, the full extent of which is quite unknown, and 

 from which the Nobundi Sobundi branch of the Panmah 

 glaciers also descends. Most interesting will it be to read the 

 account of this glacial area from the pen of a man who knows 

 the Alps so well, and has ascended so many of its peaks. He 

 has gone direct and fresh from the one to the other — what an 

 exquisite treat — and he has now seen glacial action on the 

 vastest scale it is presented at the present time in a mountain 

 chain out of Polar latitudes. My experience was the reverse of 

 this, for I had not the opportunity of seeing an Alpine glacier 

 until twenty years after I had been surveying those on the Yarkund 

 and Hunza frontiers, and in the interval the vividness of their 

 aspects and minor details had much faded. It is to be hoped that 

 Mr. Conway has with him, and used, a plane table, properly pro- 

 jected on the four miles to the inch scale, with all the peaks 

 fixed by the Trigonometrical Survey of India, correctly plotted 

 on it, and will thus be enabled to add to and correct much of the 

 previous reconnaissance work. There is no doubt, had Capt. 

 Younghusband, who was another late explorer in this part of the 

 world, worked with a plane table along his line of route towards 

 Hunza, the results of his exploration would have been of tenfold 

 value, and far more extended. The Indian Government should 

 make it a rule that all officers permitted or selected to explore 

 the unsurveyed territory beyond our Indian frontier, should, as 

 a preliminary training, do a season's work plane-tabling with a 

 Himalayan survey parly. It would also be an admirable train- 

 ing for officers selected for the Quartermaster-General's and In- 

 telligence Departments. 



H. H. GODWIN-AUSTEN. 



Nebular Spectrum of Nova Aurigae. 



Nova Aurig.« faded away so steadily in March and April as 

 to give little promise of soon again attaining any considerable 

 brightness. All the more startling, therefore, was Mr. Espin's 

 announcement of Mr. Corder's discovery that it had reappeared 

 and that he himself on August 21 had seen it as a star of the 9*2 

 magnitude with a monochromatic spectrum, presumably about 

 500 mmm. in wave-length. 



Fortunately the 15-inch refractor of this Observatory is still 

 in working order, and still more fortunately my old colleague in 

 the observation of Nova Cygni, Mr. J. G. Lohse, is staying 

 here. On August 25 and 26 we were able to examine the Nova 

 with a compound prism in the Grubb stellar spectroscope. The 

 spectrum thus seen evidently contained two bright lines, the 

 positions of which we determined as follows : — 



Chief Line: Brightness ^ to \o. 



From these we may derive the mean values of 500-3 and 

 495 '3. which prove, as we think beyond doubt, that Nova 

 Aurigae is now mainly shining as a luminous gas nebula. 



Once or twice on the 25th August, at the best moments, I 

 had noticed feeble traces of a condensed luminosity in the spec- 

 troscope, far away on the side of less refrangibility. Our time, 

 however, was fully occupied in observing the two brighter lines 

 and the zinc-lead spectrum, with which we compared them, until 

 daylight prevented further observation. On the 26th, haze and 

 bad definition concealed everything but the chief line->, but on 

 the very clear night of the 28th, continuing the observations 

 alone, I examined the star with a power of 229 on the wire 

 micrometer, and wishing to see if the spectrum had materially 

 altered I viewed the star through an excellent direct-vision 

 prism. In this way I at once saw a faint continuous spectrum 

 in the green, together with a distinct line in the yellow. With 

 the spectroscope the line was also readily perceived, but not 

 having prepared the battery for the illuminations and compari- 

 sons, no reliable direct measures could be made. By introducing 



