March 19, 1896] 



NATURE 



461 



which are far less trouble to make,, that it was only sent me yes- 

 terday. I at once used it to photograph a man's hand on an 

 inverted celluloid film, the whole enclosed in a black bag in the 

 usual way. With five inches of spark, and an exposure of three 

 minutes at eight inches distance from the film, I obtained fine 

 definition of the bones as far as the film went, including the 

 junction of the two bones of the arm with the wrist. No Tesla 

 apparatus was used. Had it been, doubtless the exposure could 

 have been considerably shortened. An area of twelve inches by 

 ten inches was covered perfectly. The tube was then set on for 

 thirty minutes without stopping with a ten-inch spark coil, 

 and showed no perceptible heating. 



Although the definition was even better, the original tube 

 with the platinum required an exposure of ten minutes under the 

 same conditions. 



I should like to draw attention to a curious dark shadow, 

 which appears to be hanging in mid-air just above the anode, 

 when the six-inch tube is set in action, and persists for some 

 lime afterwards. This shadow has the appearance of an ovoid 

 dark space surrounded by a halo, and is probably the shadow of 

 the kathode. Is it possible that rays proceed from a spot 

 coincident with this shadow ? A few rough experiments I 

 have made, seem to lend colour to this view. 



Chard, March 8. J. William Gifford. 



I SEE from a note in last week's Nature, that some little 

 doubt has been thrown upon the practical value of Rdntgen's 

 discovery in surgery. The following notes may therefore be of 

 some interest. 



With regard to the cryptoscope — after trying a number of 

 substances, I have fallen back upon potassium or barium platino- 

 cyanide for the screen ; the potas.sium salt was suggested to me, 

 and I find the shadows show up in some respects better. The 

 special form of cryptoscope which I have made is binocular, and 

 with a good Crookes' tube I have had excellent results. I have 

 been able to see distinctly shadows of the whole of the bones of 

 the upper extremities, and a good portion of the lower ; but 

 what is most intere.sting, I have been able to look straight 

 through a skull into which I had placed two or three bullets, 

 and had no difficulty whatever in seeing shadows of them, 

 although somewhat enlarged. 



With regard to the photography — I have photographed the 

 inner table of the cranium, the upper part of the spine in the 

 neck, and half the spine and vertebras in an adult. Not only 

 have I got shadows, but distinct images of the surface of the bones 

 of the spinous and transverse processes of the vertebrae ; the ribs 

 being particularly well defined. I have also photographed all 

 the joints in the body with two exceptions, and this for the 

 simple reason that I had not time to do them. 



For practical purposes exposure is of importance. Fortunately 

 the movable parts, such as the extremities, are more easily pho- 

 tographed than the denser and thicker tissues of the trunk. In 

 other words, where we require quick exposures the conditions 

 are more favourable. 



I believe the Rontgen photography, and the cryptoscope, will 

 prove to be one of the most valuable discoveries ever placed 

 before us. John Macintyre. 



179 Bath Street, Glasgow, March 16. 



While a Crookes' tube discharges an electroscope charged 

 with positive or negative electricity, when negative most 

 rapidly, I have found with several of the ordinary spectrum 

 tubes, particularly one containing oxygen, and another 

 hydrogen, that these tubes produce the Rontgen rays, but act 

 differently upon a charged electroscope. When the charge is 

 positive, the leaves collapse immediately ; when negative, they 

 open out still further. 



With the spectrum tube containing oxygen, good impressions 

 have been obtained upon a photographic plate in four minutes. 



London, March 16. F. J. Reid. 



The Huxley Memorial. 

 Since last a public announcement was made, the names of 

 Sir H. H. Johnston, K.C.B., H.M. Commissioner and Consul- 

 (Jeneral in British Central Africa, and of Mr. Charles Hose, 

 resident magistrate at Sarawak, have been added to the 

 General Memorial Committee, which now numbers considerably 

 over 700 persons, representative of science, literature and art, 

 in all parts of the world. 



NO. 1377, VOL. 53] 



The amount promised and received now exceeds ;^2300, and 

 as a sufficient sum is thus guaranteed for the statue at the British 

 Museum of Natural History and the medal at the Royal College 

 of Science, London, the first two objects of the Committee 

 definitely decided upon, Sub-Committees have been appointed 

 to carry these objects through, and designs for the statue are now 

 being prepared by Mr. Onslow Ford, R.A. 



Appeal is now being made for the third object of the 

 Committee, viz. *' the furtherance of biological science in some 

 manner to be hereafter determined, dependent upon the amount 

 collected." The foundation of exhibitions, scholarships, or 

 lectureships has been proposed, and for this purpose a 

 considerable sum will be required. The efforts of the 

 Committee to raise this are being promoted by the organisation 

 of Local Committees in all parts of the world. Conspicuous 

 among the results already obtained by this means is the receipt 

 of ;^25 from the town of Leicester, through the mediation of 

 its Literary and Philosophical Society ; and it is hoped that this 

 may be taken as a criterion of expectation from other localities. 

 Donations of any amount will be gladly received by the Hon. 

 Treasurer, Sir J. Lubbock, Bart., or by the Bankers, Messrs. 

 Robarts, Lubbock, and Co. (15 Lombard Street, E.C.), or by 

 myself. 



A circular is now printed for distribution in lecture-rooms and 

 elsewhere, and I should be very glad to communicate with 

 friends or admirers of the late Prof. Huxley, or with persons 

 connected with societies or institutions, who may be willing to 

 aid the Memorial Committee by distributing copies of this letter 

 or in any other manner. (}. B. Howes, 



Hon. Sec. Huxley Memorial Committee. 



Royal College of Science, South Kensington, 

 March 17. 



Natural History Museum. — Bird Gallery. 



May I ask when the "common people" Mr. R. B. Sharpe 

 speaks of in your issue of February 20, will "have the opportunity 

 to read, mark, learn, and inwardly digest what the Museum is 

 trying to teach"? As regards the Bird Gallery, the "oppor- 

 tunity " seems to be no nearer than it was fourteen years ago. 

 Surely there has been time during that period for the preparation 

 of a " guide" for the Bird Gallery, equally with the Shell and 

 various other departments. .4// the "common people" can 

 learn at present, is the scientific and, in some cases, the popular 

 name of the bird, and its habitat. Among the thousands of 

 species exhibited, there must be many whose history, written in 

 a few lines, as is done with the British specimens in the table- 

 cases, would be both interesting and instructive. I may add 

 that there is no " guide " to the Department of British Zoology. 



E, S. 



The Aurora of March 4. 



The fine auroral display, noticed in Nature, March 12, 

 pp. 437 and 444, was brilliantly visible from the streets of Dublirk 

 at 8 p.m. on March 4. The great beam, rising from the 

 characteristic bank of cloud into a starry sky, originated due 

 west, and, if continued, would have passed to the south of the 

 zenith. At 8.5 three or four short parallel rays, resembling a 

 gridiron, appeared in a patchy way some 20° to the north, in a 

 similarly clear sky ; they disappeared rapidly, and five similar 

 parallel bars arose close to the north side of the main ray at 

 8. ID. At 9.30 the display had faded, as far as the city was con- 

 cerned. Grenville a. J. Cole. 



Royal College of Science for Ireland. 



Inverted Images. 



Many years ago I tried the method of reading a book upside- 

 down on people who had never consciously attempted it before. 

 I was surprised at the very great difference of aptitude. Gener- 

 ally individuals who had clear recollections of form, and could 

 reproduce sketches of what they had seen more or less correctly, 

 read easily and at once ; but the greater number read slowly, 

 frequently spelling as they went along. A boy of nine years of 

 age, who was in the habit of reproducing on paper, with scissors, 

 horses, dogs, cats, coaches, &c., read upside-down at once. I 

 noticed that in cutting his patterns he sometimes cut his horse 

 upside down, but more frequently the normal way. The same 



