l62 



KNOWLEDGE \- SCIENTIFIC NEWS. 



rjii.v, 1905. 



Conducted by F. Shillington Scales, f.r.m.s. 

 R^oyal Microscopic a.1 Society. 



May i;th. — Al jo, !^;lIK>\^■r Square. Dr. Dukintifld 11. 

 Scott, F.R.S., President, in the chair. Mr. Roiisselet 

 described an old microscope of the Culpeper-Scarlet 

 type which had been presented to the Society by Mr. J. 

 L. Hazelwood. It was sigrned " Xath. Adams, Optician 

 to his Koyal Highness Frederick Prince of Wales 

 l-'erit." The date was probably about 1740, and it 

 differed from others of the type in having- four pillars 

 instead of the usual three. Mr. Rousselet also de- 

 scribed an old Adams I.ucernal microscope, made b} 

 Adams' successors, W. and S. Jones, which had been 

 presented to the Society in January by Lieut. -Col. 

 I'upman, and was exhibited in the room. The body 

 consisted of a mahogany box of the form of a frustum 

 of a pyramid about 17 ins. long and 7 ins. square at the 

 base lying horizontally. The objective was carried in a 

 sliding lube at the small end, and an eye-piece of two 

 lenses about 5 ins. in diameter was placed at the other 

 end. The stage had vertical and horizontal motions, 

 and there was a condensing system of two independent 

 lenses behind it. The curious feature about the instru- 

 ment was the method of observing the image, which 

 was by means of an aperture about ;j in. in diameter ni 

 a small disc carried by an arm that was attached to a 

 telescopic rod projecting from below the instrument 

 The distance of the disc from the eye-piece could thus 

 be adjusted until the best effect was obtained. On 

 looking through the disc, which in this instance was 

 about 14 ins. from the eye-piece, a very fair image of 

 an object placed on the stage was seen in the eye lens. 

 A communication received from Mr. D. D. Jackson, ,)f 

 New York, on " The .Movements of Diatoms and other 

 .Microscopic Plants," was read. Mr. Jackson described 

 the interesting observations and ingenious experiments 

 made by him, some with artificial diatoms, which led 

 iiim to conclude that the movements referred to arc 

 caused by the escape of oxygen gas evolved in these 

 organisms. Slides of Oribalidae were exhibited from 

 the collection presented to the Society some twenty 

 years ago by Mr. .\. 1). Michael, who, on the invitation 

 of the President, made some remarks upon that family 

 of the Acarina. 



The Microscope in the Witness Box. 



Ihe usi- cil llie niir:r(iscope as an aid to tin- m iuuliln 

 worker is .ipp.irent to everyone, and it is, ol c<jurse, 

 universally used in scientific laboratories. It will occur 

 Jo most people that it must have many uses as a means 

 of detecting adulteration in food, and that, therefore, 

 it is a valuable aid to the public analyst, but it is, 

 perhaps, not so evident that it can give equally valuable 

 help and testimony in the witness box. An elementary 

 example of the help given by the microscope in forensic 

 medicine is its use in detecting blood stains. The 

 minute red blood discs which give the red colour to 

 the human blood are not more than seven one-thou- 

 sandths of a millimetre in diameter, and are obviously 



microscopic objects, w^hile they can only be seen in un- 

 dried blood, but the microscope can be used to give 

 evidence of blood stains in quite another way. Suspected 

 bloodstains on clothing, etc.. can be treated with a little 

 alkali, evaporated to dryness, and then heated with 

 acetic acid and a minute amount of sndiuni chloride, 

 witli tlif result tliat sniaii Init cliaractoristic crystals. 



known as " haemin crystals," make lliiir appearance. 

 (Fig. I, much magnified.) 



This, however, is more an example of laboratory 

 work than of a demonstration in open court, but some 

 verv striking examples of what can be shown by the 

 microscope in cases of suspected forgery were given 

 by Mr. .Albert S. Osborn a year and a half ago, in what 

 was unfortunately the last number of the American 

 Journal oj Applied Microscopy, and I reproduce some of 

 his excellent illustrations here because they will, 1 think, 

 interest readers in this country who have not seen the 

 original paper, expressing my obligations to Mr. 

 Osborn for both illustrations and subject matter. 



For instance, as .Mr. Osborn points out. il is 

 manifest that if .1 paper were folded, and it could be 

 demonstrated that part ol the writing was made after 

 such folding, strong suspicion would be cast upon the 

 docimicnt. 'ITiis might be shown by a liny 

 amount of ink spreading into the crease and c\ en reach- 

 ing the other side of tin- paper, and it would be f|uite 

 unmistakable. 



Similarly, fr.audulent additions to documents may be 

 shown to have been written with a different pen, or at 

 a different tiine, or under different conditions, by 

 measuring the width of the unshaded strokes and 

 observing that they differ from those of the original 

 writing. .Such measurements arc readily made up in 

 the ten-thous.indth of an inch, or less. 



