February 20, 1S96] 



NATURE 



379 



placed my sensitive plate in a metal box with an aluminium 

 window in it. The whole was well earthed. This precaution 

 was taken to prevent any sparking inside the box. The box 

 was placed between the poles of my Wimshurst machine, and 

 photographs of various objects taken. This is, I think, con- 

 clusive that the influence at work is not the ordinary electrical 

 waves or discharges. For in a carefully-closed metal box there 

 can be no electrification, neither do the photographs of metal 

 objects show any trace of discharge or sparking." 



The following important communication on " Photography 

 through Opaque Bodies without Crookes' Tube" has been 

 received from Dr. John Macintyre : — 



"At the demonstration given by Lord Blythswood and Dr. J, T. 

 Bottomley before the Glasgow Philosophical Society on Feb. 5, 

 I was requested to show some results in shadow-photography 

 obtained by the use of comparatively simple apparatus. My 

 remarks were then intended to show that as we became familiar 

 with this new art the apparatus would become less complicated. 

 As the present notes are written for another purpose I simply 

 mention the fact that the experiments noted below were made 

 with the same apparatus exclusive of Crookes' rube. It con- 

 sisted of an induction coil giving not more than a two-inch 

 spark, the primary coil of which was excited by four small 

 secondary cells giving two volts each ; a very small Tesla coil 

 made by Messrs. Baird and Tatlock ; and a Crookes' tube 

 selected from the stock of an instrument-maker, but not specially 

 prepared. 



" Lord Blythswood on that occasion described the experiments 

 published in the last issue ctf Nature by means of which he 

 was able to demonstrate that photographs could be taken without 

 Crookes' tubes. Mr. Sydney D. Rowland in his interesting 

 contribution to the subject in the same issue raises the question 

 of the possibility of a ' contact phenomenon ' being the ex- 

 planation of Mr. Clifford's results, and not Rontgen's rays at all. 

 As the same douljt was suggested to my mind as the result of 

 my own experience I should like to record the. following experi- 

 ments which were made by me with a view of confirming the 

 extremely interesting results recorded by Lord Blythswood. In 

 doing so I wish it clearly understood that I do not suggest that 

 the photographs taken through opaque bodies by Lord Blyths- 

 wood were not the result of Rontgen's rays ; my statements 

 simply bear u{X)n my own experience and the results I have been 

 al)le to obtain. 



*' In my first experiment the sensitised paper was enclosed in a 

 mahogany box, the sides of which were three-sixteenths of an 

 inch thick, and the object to be photographed was a perforated 

 zinc plate ; bromide paper was substituted for glass plates in order 

 to do away with resistance, and the whole was placed between 

 the terminals of the small Tesla coil. The current coming from 

 the negative pole before reaching the positive had therefore to 

 pass through the following structures : (i) Three-sixteenths of an 

 inch of mahogany, (2) a .sheet of aluminium one-sixteenth of an 

 inch thick, (3) the zinc plate, (4) the bromide paper, {5) some 

 black cardboard for packing, (6) the other end of the box, also 

 three-sixteenths of an inch. The box was insulated from the 

 earth and held between the poles for ten minutes. On develop- 

 ing, a distinct image of the plate was obtained, the perforations 

 showing black on the paper, while the part upon which the zinc 

 rested had not been acted upon at all. It 'vas clear from this 

 experiment that I had obtained a photograph without a Crookes 

 tut)e, and a negative — that is to say, had it been printed from the 

 liiimide paper we would have had a reproduction of the original 

 perforated plate. 



• • The second experiment was different from the first inasmuch 



I placed a metal plate behind the bromide paper, and con- 



luently there was the following arrangement proceeding from 



ic negative to the positive pole : (i) The end of the mahogany 



i>o\, (2) the aluminium plate, (3) the zinc perforated plate, (4) 



the bromide paper, (5) a copper disc, (6) black cardboard for 



"-king, (7) the other end of the mahogany box. This was 



lin placed between the terminals of the Tesla coil for the 



lie time, and the bromide paper developed in the usual way. 

 I iiis time the perforations did not mark the paper, but I had a 

 distinct impression of the zinc ; in other words, I had obtained 

 I positive, because, had I printed a copy, the perforations 

 would have appeared black, quite the reverse of the last 

 experiment. 



"It will be observed that in neither case had I, like Mr. 

 Sydney Rowland, connected the positive pole of the coil with 

 the metal plate behind the sensitised surface. 



NO. 1373, VOL. 53] 



" On submitting these results (which were obtained previous 

 to the date of Mr. Sydney Rowland's letter) to Lord Kelvin and 

 Dr. Bottomley they agreed with me that the picture had pos- 

 sibly not been taken by means of Rontgen's rays at all ; and 

 Lord Kelvin suggested the following third experiment, in which 

 the sensitised paper was enclosed in a metal box. In this ex- 

 periment the following structures were placed in definite order 

 between the negative and positive pole : ( i ) The front of the 

 mahogany box, (2) several layers of black paper, which formed 

 a covering for the metal box, (3) the front of the metal box, 

 (4) the zinc perforated plate, (5) the bromide paper, (6) the 

 metal plate, (7) the back of the metal box, (8) the black paper 

 surrounding the metal box, (9) the other end of the mahogany 

 box. 



" It will be noticed that in this experiment the metal plates in 

 front and behind the bromide paper were enclosed in a metal 

 case which attracted the current round it. The result was as 

 we had anticipated, because repeated attempts with different and 

 prolonged expo.sures failed to produce any impression whatever 

 upon the bromide paper. 



" Had the photographs been obtained by the X-rays, one might 

 have expected that while the current was conducted past the 

 sensitised paper some impression would have been got by the 

 Rontgen's rays piercing the metal box. As yet, however, I 

 have not been able to obtain this result, although I have tried to 

 with thin aluminium sheets in contact with each other at the 

 edges and enclosing tlje metal plates and bromide paper. 



" I should like to point out that Lord Blythswood's experi- 

 ments differ from the above in many respects. He used glass 

 sensitised plates ; the apparatus was exceedingly powerful ; and 

 the objects were not placed between the terminals of the 

 machine, but at some distance below the line of the sparks. 



"From the above-mentioned experiments it is clear (i) that 

 photographs may be taken without Crookes' tubes; (2) that 

 different results may be obtained according to the conditions to 

 which the sensitised surface is subjected. And I would suggest 

 the following questions as suitable for further investigation : — 

 {a) Are they not the result of a force different from the Rontgen's 

 rays ? {b) what is this force which is now described as a ' con- 

 tact phenomenon ' — a term, of course, which does not explain 

 the actinic power ? (c) what is the actinic power which we have 

 hitherto considered to be a property of ordinary light ? (d) were 

 Rontgen's rays not generated between the metal plates ? 



" There is one point in this experiment which has not been 

 touched upon by other writers, and which I should like to allude 

 to in conclusion. It is quite clear, whether the photographs 

 produced without Crookes' tubes were obtained by means of 

 Rontgen's rays or not, that a current may be conducted through 

 metal plates to a sensitised surface and impressions obtained 

 thereon. In Mr. Sydney's Rowland's letter he makes no 

 mention of metal plates having been placed in front of the 

 sensitised plates. I have placed three plates of different metals 

 in front of the object to be photographed during the time of 

 exposure and obtained a picture, so that we have here a method of 

 photographing certain objects through opaque bodies in the form 

 of metal plates, and, theoretically speaking, the thickness would 

 be a matter of comparatively little importance." 



Prof. J. Wertheimer, Principal of the Merchant Venturers' 

 Technical College, Bristol, has, at the suggestion of Mr. C. A. 

 Morton, Surgeon to the Bristol Ceneral Hospital, taken a radio- 

 gram of an amputated foot into which Mr. Morton had introduced 

 nine foreign bodies (bullets, splinters of needles, and glass 

 wedges). Six ot these were plainly .seen on the radiogram, 

 although Mr. Morton found that a fellow-surgeon could only 

 locate one by palpation. 



Prof. Wertheimer says : " Two points of interest arise 

 on examination of the radiogram. Mr. Morton had 

 endeavoured to place a fragment of needle through the 

 last joint of the great toe on its plantar aspect. On 

 dissecting the foot, after the radiogram had been 

 taken, he found that the fragment had penetrated the inner 

 corner of the distal end of the first phalanx, and had passed 

 beneath the bone, leaving a small portion embedded in the 

 phalanx itself. This fragment shows up plainly in the radio- 

 gram, and, as the foot rested on its plantar aspect, the rays must 

 have passed through the whole thickness of the bone. The 

 radiogram does not, however, show that the needle is beneath 

 the bone. It appears, therefore, that in such cases two radio- 

 grams will be needed— one taken with the dorsal, and the other 

 with the plantar aspect uppermost, the conditions being other- 



