74 



KNOWLEDGE. 



[April 1, 1896. 



experiment — which the reader should trj' — shows why 

 some of the earliest hands appeared so large and had such 

 " woolly " or iudistinet outlines. 



The subject to be operated on is taken into the dark 

 room. A sheet of celluloid or mica is laid over the film of 

 a sensitive plate ; the hand, if that is to bo the part electro- 

 graphed, is laid on the celluloid, and the whole enclosed 

 in a blin'k cloth bag, tied tightly rouud the wrist, so that 

 no light may get at the plate. The plate may then be 

 taken into broad daylight not bright sunshine — and laid, 

 wilh the patient's hand upon it, on a table over which the 

 bulb is hung. I use a small wooden stand, of the size of 

 a whole plate, with a ledge on one side to prevent slipping, 

 attached to one end of which is a glass rod in the form of 

 an inverted L, from the horizontal arm of which the tube 

 hangs. In some experiments no celluloid was used, and 

 in more than one case the warm moisture of the hand 

 partially melted the gelatine. In others a paper bag made 

 of grocer's paper was slipped over the plate to prevent 

 contact. The paper meant is the greased paper used for 

 wrapping up butter, and this is supposed to be quite 

 waterproof ; but in some cases the grease melted, and the 

 last state of that plate was worse than the first. With a 

 cool hand paper is better, for it is less slippery; but with a 

 hot one ?jiica or celluloid is best. Both the latter are so 

 transparent to the rays which do the work that a mica 

 disc and a piece of celluloid laid on a plate and electro- 

 graphed are barely visible in the negative. The exposure 

 varies according to the thickness of bone and tissue to be 

 penetrated, and according to the moisture in the air. 

 No pain is felt beyond a slight cramp, or "pins and 

 needles," owing to the limb being kept in one position so 

 long. After exposure the plate is developed and fixed as in 

 ordinary photography. 



Among the subjects hitherto electrographed with my 

 apparatus are, of course, a large number and variety of 

 hands, some well- and some ill-formed. This is the easiest 

 living subject. Several feet have been taken, some elbow 

 joints, a club-foot, living cats' and dogs' paws, a flatfish, 

 a rabbit's shoulder (dead) showing a shot jammed between 

 the small bones, and a boy's forearm with several shot 

 embedded just below the elbow. The accompanying prints 

 of a sparrow (Fig. 1 and Fig. 2) illustrate one of the 

 peculiarities of eleetrography. The two prints are from the 

 same bird, one photographed in the ordinary way, and one 

 electrographed. The first shows no peculiarity, but the 

 second looks like a half-hatched chick. Although it was 

 known that feathers were transparent to the new rays, the 

 result at first seemed startling. The sparrow, when dead, 

 was laid flat so as to show the ventral aspect. 8ome con- 

 fusion of image is caused by the bones of the back appearing 

 through those of the front. The merrythought is plamly 

 visible and the breast-bone. The round black thing is 

 supposed to be the gizzard. This print is important on 

 account of its indications of internal organs, which have, 

 so far as 1 know, never before (February 29th) been electro- 

 graphed inside an entire animal. The illustrations of a 

 mouse show internal organs still more clearly. The first 

 one ( Fig. 3) is the ventral aspect. It shows the attachment 

 of the hind legs and the vertebrae of the tail especially well. 

 It also seems to show signs of Imigs, liver, and kidneys. 

 The second one (Fig. 4), in profile, shows the dental 

 formation of the rodent, and, still more clearly, the internal 

 organs. As the mouse in this case was laid on its side, 

 the legs furthest from the plate are, of course, incUstinct. 

 No others of my negatives differentiate so well between the 

 different structures, and, in most of them, only the ditt'erence 

 between bone and flesh has been visible. 



The child's hand and forearm (Fig. G) illustrates the 



incomplete ossification proper to the age. As it was a 

 child of six, it was diilicult to keep the hand perfectly still 

 for ten minutes, and the outline is, therefore, somewhat 

 indistinct. The "growing places" between the phalanges 

 of the little finger are well shown. Here the bone is still 

 in a cartdaginous state. 



The adder (Fig. 5) was laid on its back and pressed well 

 on to the plate, but being somewhat crushed with packing, 

 and having stiffened after death, it did not touch quite 

 evenly, llencu a little indistinctness here and there. The 

 head is remarkably well defined, every bone being distinct, 

 and the fangs appear clearly. 



For a hand from ten to fifteen minutes gives good results, 

 for a foot from thirty to fifty, and for an elbow about the 

 same. The cat objected at the end of four minutes, and the 

 dog at the end of seven. The cat's paw, though a thin 

 negative, was quite clear ; but the dog had evidently twitched 

 a little. In these cases the paws were fastened to the plate 

 with two elastic bands, and the paw held well out from 

 the body of the animal. The paw was tightly gripped, 

 and the bag tied round the wrist of the holder above the 

 animal's shoulder, so that both paw and hand were inside 

 the bag. Something of this sort would be necessary in 

 any attempt to electrograph a baby's limb. No fur is 

 shown in any of the negatives. A foot can, of course, be 

 electrographed through a stocking ; but the edges of the 

 stocking show, and the definition is slightly impaired. 

 The elbow joint and the club-foot, being thick, did not give 

 good definition, for the further from the plate the more 

 " woolly" the outline. The flatfish was a small dab, and had, 

 unfortunately, been cleaned, so that the viscera are not 

 there ; but the bones show through the flesh and skin as 

 clearly as though it was made of glass. In many of the 

 hands and feet the bones show clearly down to the wrist 

 and ankle. In one case, the back of a lady's hand, which 

 had a long exposure, the bones of the wrist look as though 

 they were cut out in stone, they are so distinct ; and the 

 ankle bones in one foot are no less clear. 



In the case of an invalid it will probably be impossible 

 to get such fine definition, for only one or two of the 

 subjects tried have proved such good sitters as the lady 

 mentioned above. Invalids are usually nervous and inclined 

 to twitch, or they have hot, moist hands or feet, or their 

 malformation renders it difiicult, as in the club-foot, to 

 lay the part well on the plate. For taking a foot, a chair 

 placed on a table is used ; but for the club-foot, as the side 

 of the foot was to be taken, a table, with a mattress on 

 which the patient lay, was employed, and the leg strapped 

 to the table. The part of the limb electrographed is not 

 the part next to the tube, but that next to the plate. 

 This is obvious if one remembers that it is a shadow. 

 Thus, the hands are all palms and the feet are all soles 

 unless special arrangements are made. The distinction 

 between bone and flesh is very marked, but I have never 

 seen any sign of a nerve or blood-vessel. If these were 

 ever visible, one would have expected to see them in the 

 forearm with the shot, or in one of the elbow joints, which 

 have been taken in various positions, and in which part of 

 the body the vessels must be large enough to show. 



As regards the tube, I used at first a Crookes tube, which 

 I had bought more than fourteen years ago. With this 

 I make almost continuous exposures, stopping every five or 

 ten minutes to feel the terminals of my tube, and unless they 

 are hot, which is seldom the case, I go on again at once. 

 My tubes are much larger than those now sold in England. 

 I used only two for all my early experiments. The first 

 one seemed to be deteriorating ; it became increasingly 

 difficult to get the spark through, so I tried another. That 

 gave splendid results for about a fortnight, and then began 



