Oct. 27. 1855.] 



NOTES AND QUERIES. 



333 



prepare, during the evening, fifteen or twenty plates for 

 use the next day, without anj' box with slides, or any 

 Other apparatus ; which is certainly a great simphfication, 

 particularly when on a tour. 



" If one is in a hurry, the plates may be dried over a 

 spirit-lamp or a furnace, as I have frequently done, with 

 observing any diminution in the sensitiveness or finish of 

 the negatives. This method of drying is at the same 

 time useful to prevent the bubbles or partial risings of the 

 albumen, which are occasioned, I believe, by the yolk of 

 the egg being mixed with the white. With regard to the 

 necessity of keeping in the dark the plates of albumenized 

 collodion, but whicli have not been immersed in the second 

 bath, I will mention a curious experiment which I made, 

 in consequence of having by mistake employed for a por- 

 trait a plate which had not received its last bath of aceto- 

 nitrate. I exposed a similar plate for half an hour to the 

 light of the sun ; I then immersed it in the last bath, and 

 I obtained a picture which did not differ from one ob- 

 tained in the ordinary way. Not having had time to 

 make a sufficient number of experiments to determine 

 ■whether it is necessary to keep the plates collodionized 

 and albumenized, but which have not been in the last 

 bath, in the dark, I leave it to other photographers to 

 settle this question, which is not without interest as re- 

 spects the manipulations when one is on a tour. 



" As to the employment of gallic or pyrogallic acid, it 

 should be stated that the first gives, as 1 have said, much 

 stronger contrasts, and is useful, when the light is dull, to 

 make the lights come out, and to break the uniformity of 

 the tone. If, on the contrary, one is working in full sun- 

 shine with strong oppositions of light and shade, pyro- 

 gallic acid, to which a large proportion of acetic acid has 

 been added, is the best. 



" Lastly, with regard to the rapidity, I repeat, what I 

 have already said, that I have found it as rapid as with 

 collodion alone, which I have prepared myself with iodide 

 of ammonium only, which does not give me a portrait in 

 less than a minute with one of Lerrebour's lenses and a 

 moderate light. I have seen others work with a much 

 more rapid collodion than mine, and I do not know whe- 

 ther the iodized collodion has the same rapiditv. How- 

 ever this may be, after the different groups that I have 

 obtained in from six seconds to one minute, and after the 

 landscapes, and interiors which neither collodion alone 

 nor albumen have enabled me to take, I hope that this 

 new process, which appears to me to unite the advantages 

 of two known processes, will justify the fovour with which 

 it has been received by all photographers. 

 " J. M. Taltenot, 



" Professeur de chimie au Pyrtan^e 

 Imperial Militaire." 



_SingIe Stereoscopic Pictures (Vol. xii., pp. 171. 212. 251. 

 273.).^ — Mr. Shadbolt, who is entitled to speak ex ca- 

 thedra on the subject, has generously and courteously 

 placed Mr. Norman's suggestion in the position of an 

 interesting question for discussion. I cannot by any 

 theory give my adherence to Mr. Norman's method of 

 taking a single stereoscopic picture, and at this season, 

 with the entire day occupied in business, I am unable to 

 bring it to the test of experiment ; neither can I under- 

 stand the "wonderfully stereoscopic effect" of a single 

 picture " when viewed by one eye only," as testified by 

 Mr. Shadbolt. But it does not thence follow that both 

 these gentlemen are wrong, and that I am right. Allow 

 me to add one or two remarks to what I previously com- 

 municated. 



1. Distinction must be made between mere increase of 

 intensity in a picture, and absolute stereoscopic effect. 



2. It may be possible, « with proper precautions," and 

 under certain conditions, to superpose two perfectly 



No. 313.] 



similar images, and obtain one image of greater in- 

 tensity. 



3. It is not possible (if T have understood my own ex- 

 periments, and apprehended optical science rightly) to 

 obtain, on Mb. Norman's plan, what can properly be 

 called a stereoscopic picture ; the difference of angle being, 

 in my estimation, so inappreciable, that his picture can 

 be nothing else than the superposing of two (virtually) 

 similar images upon each other. 



But there is something exceedingly interesting in Mr. 

 Norman's suggestion, and Mr. Shaubolt's comment, as 

 regards increase of intensity. I have the faculty of 

 squinting, which makes me in a good degree independent 

 of the stereoscope. I place on the table two half-crowns, 

 the same side upwards, in the same position, and about 

 two inches apart. 1 cross the axes of the eyes, and pro- 

 duce an intermediate image of great intensity, and of 

 diminished size. The increase of intensity is the result of 

 light upon light, and shadow upon shadow, and reduced 

 apparent dimensions. lam so accomplished asquinter, 

 that I can separate the half-crowns by an interval of six 

 inches, and yet superpose the images, and the interme- 

 diate image is then reduced to a size something between 

 a florin and a shilling. In place of the half-crowns I 

 have taken pairs of other things, including small en- 

 graved landscapes and portraits, and with the same effect. 

 It is worthy of remark, that when two pictures are united 

 by the stereoscope, the image produced is likewise smaller 

 in its dimensions. Hence it appears to me that there is 

 a double effect produced by the two pictures when sub- 

 mitted to the stereoscope : there is the intensity arising 

 from superposition of images and reduction of size, and 

 there is the angular difference producing the stereoscopic, 

 or seeing round, effect. I offer these remarks neither in 

 the spirit of contradiction, nor as a self-elected umpire, 

 but simply as a contribution towards the discussion and 

 settlement of a question, which no thoughtful photo- 

 grapher or optical inquirer can regard with indifference. 



Thomas Kosk. 



What does Mr. Shadbolt mean when he states, as a 

 fact, that in a single picture " all the parts are equally dis- 

 tant from the observer " ? (The italics are his.) 1 sup- 

 pose he means something more than he says, for the 

 statement, as it stands, is either ambiguous or incorrect. 

 C. Mansfield Ingleby. 



Birmingham. 



^tpliti t0 ^{n0r ^itetieS. 

 Legend of County Clare (Vol. ix., p. 145.; 

 Vol.xL, p. 455.). — In No. 293. is a Note from 

 Y. S. M. relative to a legend of the co. Clare, 

 contributed by me to Vol. ix., p. 145., in which 

 the similarity of my legend, and that published 

 and also dramatised by Lover, under the title of 

 The White Horse of the Peppers, is noticed ; and 

 Y. S. M. further asks if I would mention the 

 name of the family to which my legend referred. 

 To this I replied, that as the family are still in 

 possession of the property said to have been 

 gained so cleverly, 1 did not feel quite disposed to 

 publish the name; that the village where the 

 event took place was named Kilfenora, remark- 

 able for its very ancient cathedral, and for several 

 stone crosses, some of which were removed to 

 Clarisford House, Killalloe (the bishop's palace), 



