254 



NA TURE 



[!^ti/y 30, 1874 



giving an account of his experiences, made an appeal to the 

 meeting for increased support to carry on the work of explora- 

 tion, which was at present flagging for want of funds. lie urged 

 the subscribers to the Fund to complete the work of surveying 

 the country as soon as possible, as the land, being so fertile, was 

 constantly being taken by the Greeks and other foreign culti- 

 vators of the soil for farming purposes. As a consequence, the 

 old names of the towns and villages were fast disappearing, and 

 the whole country was assuming a different aspect. This meet- 

 ing was the first of a series that is to be held, information as to 

 which can be obtained of the secretary at the office of the Fund, 

 9, Pall Mall East. 



According to the [State geologist of Minnesota, the creta- 

 ceous lignite beds of Minnesota Valley are likely to afford valu- 

 able coal mines. 



In the report to the Admiralty of Capt. O. S. Nares, of 

 H.M.S. Challaiga-, dated Melbo\irne, March 25, 1874, Capt. 

 Nares, speaking of the temperature of the ocean, especially 

 near the pack edge of the ice, says: — "At a short distance 

 from the pack, the surface water rose to 32°, but at a depth of 

 40 fathoms we always found the temperature to be 29°; this 

 continued to 300 fathoms, the depth in which most of the ice- 

 bergs float, after which there is a stratum of .slightly warmer 

 water of 33° or 34". As the thermometers had to pass through 

 these two belts of water before reaching the bottom, the indices 

 registered those temperatures, and it was impossible to obtain 

 the exact temperature of the bottom whilst near the ice, but the 

 observations made in lower latitudes show that it is about 31°. 

 More exact results could not have been obtained even had iMr. 

 Siemens' appar.atus been on board." It seems to us that the 

 difficulty mentioned is one wliich would certainly have been sur- 

 mounted by Messrs. Negretti and Zambra's new recording thtr. 

 mometers, a description of which appeared in Nature, vol. ix. 

 p. 387; this being exactly one of the cases to which this instru- 

 ment is peculiarly adapted. We believe the inventors and 

 makers have greatly improved their t'lermomeler since our 

 description appeared, and no doubt means will be taken by the 

 Admiralty to transmit one to the ChalhiigLT. 



Mr. Pll.USCllER, optician and scientific instrument maker, of 

 New Bond Street, W., has been decorated by the Emperor of 

 Austria with the golden Cross and Crown of Merit, as are cogni- 

 tion of his Majesty's approval of the superior quality and 

 precision of his scientific instruments shown at the late Vienna 

 Exhibition. 



The following is a list of candidates successful in the compe- 

 tition for the Whitworth Scholarships (Science and Art Depart- 

 ment), 1874 :— William Martin, metal turner, Wolverton ; 

 Robert A. Sloan, engineer's apprentice, Birkenhead ; William 

 Sisson, engineer, Gateshead ; Frederick Stubbs, engineer's 

 apprentice, Derby ; Thomas L. Daltry. drauglitsman's appren- 

 tice, Newcastle-on-Tyne ; Frederick fl. Livens, engineer's 

 apprentice, Gainsborough. 



The additions to the Zoological Society's Gardens during the 

 past week include two Tigers (Fdis ligris) from Calcutta ; two 

 Yellow-billed Sheathbills {Chionis aiha) from the Southern 

 Ocean, presented by Mr. H. Roberts ; a Wanderoo Monkey 

 (Macacus silaius) from the Malabar Coast, presented by Lieut. 

 Vipan ; a Rose-crested CockatoJ (Cacalua moliicceiisis) from 

 the Moluccas, presented by Mr. John Elms ; three Grey-breasted 

 Parakeets (Bolhorliyncus iiwnachus) from Monte Video, pre- 

 sented by Mr. C. I'urnchard ; a King Vulture (GypaTchiis p,tpa) 

 from Tropical America ; a Red-backed Buzzard (liuleo ciytliro- 

 notus) from South America, purchased ; a Philantomba Antelope 

 (Cephahyplnis iiia.x-.oJlii) born in the Gardens. 



ON SPECTRUM PHOTOGRAPHY* 

 II. 

 T NEXT come to a very beautiful reflex action of spectroscopy 

 on photography ; and now I must take you back to America, 

 I am nearly certain that everyone in this room is perfectly familiar 

 with the name of Rutherfurd in connection with celestial photo- 

 graphy : if you will allow me I will point my reference to 

 him by throwing on the screen one of his magnificent photo- 

 graphs of the moon, which he was good enough to give me some 

 little time ago. Unfortunately, I am not able tothrow on the screen 

 a photograph of the solar spectrum which we owe to him, the most 

 magnificent jihotograph — and I say it with the intensest envy — • 

 which I think it is possible to obtain. However, I have a copy of 

 it on the wall, and it is well worth inspection. Rutherfurd, whose 

 name is associated with that of Delarue in the matter of celestial 

 photography, was not content with reflectors. He lives in the 

 centre of New York, and I suppose New York is as bad as London 

 for tarnishing everything that the smoke and atmosphere can get 

 at ; and he came to the conclusion that he must abstain from celes- 

 tial photography altogether, or else make a lens — and a lens with 

 Mr. Rutherfurd means something over 12 in. diameter — 

 which should give him as perfect an image in New York 

 with 15 in. of glass, as a perfect reflector of 15 in. aperture 

 would give him as far away from a city as you please. Mr. 

 Rutherfurd, who never minces matters, knowing that it was ab- 

 solutely impossible to get such a lens as this from an optician, 

 who of course neglects almost entirely the violet rays — the 

 very rays which he wanted — in constructing an ordinary tele- 

 scope, determined to make such an one himself. He thought 

 about the matter, and he cime to the conclusion that in any 

 attempt to correct a lens of tliis magnitude for the chemical rays, 

 the use of the spectroscope would be invaluable. He therefore 

 had a large spectroscope made, in order to make a large tele- 

 scope, and then we have just as distinct an improvement upon 

 the instruments which we owe to the skill of those who first 

 adopted the suggestion of Sir John Herschel and brought to- 

 gether the chemical and the visual rays, as the improvement \\c 

 owe to Ilerschel was upon the instruments which dealt simply 

 with the visible rays. Mr. Rutherfurd simply discards the 

 visual rays, and brings together the chemical rays ; the 

 result of bis work being a telescope through which it is 

 impossible to see anything, but through which the mi- 

 nutest star, down I believe to the tenth magnitude, can be 

 photographed with the most perfect sharpness. This is the 

 instrument of the future, so far as stellar astronomy is con- 

 cerned. Having thus achieved what he wished in the construc- 

 li m of this instrument, and having the spectroscope, Mr. 

 Rutherfurd commenced a research, which, I am sorry to say, 

 he has never published, for it ivould be of the greatest value 

 to any photographer or any astronomer amongst us, upon 

 various kinds of collodion and upon the best arrangement 

 of lenses for pliotographing the spectrum. Mr. Rutherfurd 

 found that some collodions which he got were so local in 

 their action as to be almost useless for that reason, and 

 that others were so general in their action tliat they were 

 also almost useless for the exactly opposite reason. I will 

 now throw on the screen the line G and the lines in the 

 green, or rather the lines approaching to the green near F ; 

 with ordinary collodions, such as one generally gets, that 

 is to say, collodions not absolutely good, but free from both 

 the extremes referred to by Mr. Rutlierfurd, we want something 

 like five seconds for the part near the line G. Well, when you 

 go a little way along the spectrum in the less refrangible direc- 

 tion, you have to put minutes for seconds — in other words, the 

 exposure has to be sixty times as long. I have another photo- 

 graph of the spectrum, which will show you the part of the sp'c- 

 irum less refrangible than the line F to which I have referred. 

 This photograph which you see on the screen required an ex- 

 posure of very nearly half an hour. 



Those of you who are most familiar with the solar spectrum 

 will recognise the extreme importance of Mr. Rutherfurd's con- 

 tiibution to photographic spectroscopy, when I tell you that 

 his jihotograph of the solar spectrum is quite as admirable and 

 excellent as is the photograph of the moon which I have just shown 

 you on the screen. During the last year this question of the solar 

 spectrum has again been considerably advanced by photography 

 in America. Mr. Rutherfurd's photographs, admirable although 

 they are, are refraction photographs, that is to say prisms wer e 



* Continued rrom p. 113. 



