July 4, 1884.] 



SCIENCE. 



ever, and as such a self-evident piece of stupidity as 

 to render further discussion useless. 



Mr. Fitzgerald further says that Professor Wood 

 has pointed out my mistakes. Is he willing to say 

 what mistakes ? I am convinced that Mr. Fitzgerald 

 has never read any criticism by Professor Wood which 

 he is willing to indorse; but, since he has himself 

 made reference to these criticisms, I now ask Mr. 

 Fitzgerald to state which of Professor Wood's posi- 

 tions against me he regards as sound. I do not believe 

 he can find one. 



Mr. Fitzgerald is unable to find any excuse for me 

 when I introduce the idea of a pencil of rays of in- 

 finitesimal angle, unless it be that I have overlooked 

 the fact that the energy of such a pencil is infinitesi- 

 mal. I beg leave to say that the excuse and the 

 assumption are both entirely gratuitous on his part, 

 and not in accordance with the facts. In the algebraic 

 investigation made in the original paper, as well as in 

 that given above, the angle is not assumed to be in- 

 finitesimal, or even small. The sole excuse, and the 

 real one, was that it was a form of argument which 

 it seemed to me would put in a clear light the truth 

 which I had otherwise established, that such a process 

 as had been proposed would heat B at the expense 

 of A. 



In conclusion I may be permitted to say, that when 

 Mr. Fitzgerald attempts to treat the controversy 

 which he has himself inaugurated as not worth his 

 consideration, and gives notice that he therefore 

 thinks it not worth while to continue it, he must 

 know that he lays himself open to the suspicion that 

 poverty of arguments, and not disinclination to con- 

 troversy, leads him to this decision. If Mr. Fitz- 

 gerald regards it as compatible with his dignity to 

 beat a retreat on any such pretext, I, for one, cannot 

 agree with him. H. T. Eddy. 



Cincinnati, June 10. 



Temperature of the spheroidal state. 



In some experiments made to determine this point, 

 to avoid radiation, the temperature was measured by 

 a thermo-electric couple, as in Mr. Hesehus's studies. 

 The element used was composed of german-silver and 

 iron, No. 22 wire. The wires were hard soldered 

 together, and then bent into a loop, and inserted in 

 a glass tube filled with plaster-of-Paris. The tube 

 was about twelve centimetres long and five millimetres 

 bore; and the polished loop projected about eight 

 millimetres, with a width of four millimetres. This 

 element was connected directly with a reflecting gal- 

 vanometer with twenty-five ohms in circuit. The 

 spheroids were formed in a spoon heated over a spirit- 

 lamp, and no special precautions were taken to secure 

 equal temperatures. The loop was plunged in the 

 spheroid, and deflection noted. Ten readings were 

 thus taken with very small variations, and then the 

 loop was placed in a beaker of water almost in con- 

 tact with the bulbs of two thermometers. The water 

 was then heated till the deflection was the same as 

 that given by the spheroid, and the thermometers 

 were read at this point both while heating and cool- 

 ing. The variations of temperature were less than 

 1°; and this part of the experiment was repeated 

 several times. The whole experiment was repeated a 

 number of times on different days, with results all 

 within 1°. 



The temperature thus found was, for water, 90°, 

 and for alcohol, 69°. 



The size of the spheroid had no effect on the tem- 

 perature, as the deflection remained constant as long 

 as there was enough liquid to protect the loop from 



radiation. In the case of alcohol, the globule could 

 be surrounded with vapor-flames until greatly reduced 

 in size, without visibly increasing the deflection. 

 Ether was experimented on; but the temperature 

 proved to be so low, barely above that of the room, 

 that no satisfactory results could be obtained. 



The series of experiments hints at a lower and less 

 variable temperature than has usually been assigned 

 to the spheroidal state. Louis Bell. 



Dartmouth college, June 9. 



The inventor of the vertical camera in 

 photography. 



In Science, No. 70, Mr. G. Brown Goode says, con- 

 cerning the invention of the vertical camera, " As 

 a matter of fact, the vertical camera now used for 

 photographing natural-history specimens, etc., is the 

 outcome of a suggestion made in December, 1869, by 

 Professor Baird." 



As this letter is written to put on record the history 

 of the invention of the vertical camera, it is neces- 

 sary, in justice to myself and other inventors of a 

 vertical camera, to state that the notes concerning 

 the history of the invention were omitted from my 

 original article {Science, No. 62) at the suggestion of 

 the editor. The facts concerning the invention and 

 use of the vertical camera known to me at present 

 are as follows : — 



In 1863 J. Gerlach published ' Die photographie 

 als hilfsmittel zu mikroskopischer forschung,' in 

 which was figured and described a vertical camera. 

 In 1866 Montessier, in ' La photographie appliquee 

 aux recherches micrographique,' described and fig- 

 ured a very much improved vertical camera. Both 

 of these are figured and described in Frey, ' The mi- 

 croscope and microscopical technology' (New York, 

 1872). In 1872 John C. Moss invented a swinging 

 vertical camera, which was described and figured in 

 the U. S. patent-office report, October, 1877, p. 961, 

 plate page 279. This camera was also figured in 

 the Scientific American (1877) and in Leisure hours 

 ( 1879). In 1877 also appeared a description and figure 

 of a vertical camera by Schaefer, in ' The microscope 

 and histology,' p. 295. The above, together with the 

 letter of Mr. Goode, the note concerning Dr. Danna- 

 dieu's camera, and the papers by myself, constitute, 

 so far as I know, all the published notices of a verti- 

 cal camera. 



By the courtesy of the gentlemen named below, I 

 am enabled to make important additions to the his- 

 tory of this subject. John C. Moss, president of the 

 Moss engraving company, in a private letter, says, 

 " I remember having used a camera in a vertical 

 position in 1858 to copy daguerrotypes and tintypes. 

 ... I also used the same arrangement to photo- 

 graph some shells and other small objects." Dr. 

 Deecke says, "I have used the camera in a vertical 

 position since 1873. The simple alterations on the 

 camera were devised by myself, and executed in the 

 shops of the asylum." Prof. E. Ramsey Wright, of 

 Toronto university, also uses a vertical camera; but 

 the date of its invention by him is not known to me. 

 To briefly summarize: the'first figure and description 

 of a vertical camera known to me were those of Ger- 

 lach, in 1863; while the first to use the vertical camera 

 was John C. Moss, in 1858. Every person using this 

 instrument, so far as appears at present, was an origi- 

 nator, but John C. Moss, seems to have been the 

 originator, of the idea of a vertical camera. 



Simon H. Gage. 



Ithaca, June 21. 



