February. IPIO. 



KNOWLEDGE. 



73 



MICROSCOPY. 



By A. W. Sheppard, F.R.M.S., 

 with tJic assistance of the foUoicing in icroscopists : — 



Ar'ihur C. Eanfield 



James Burton, 



The Rev. E. W. Bowell, M.A. 



Charles H. Caffvn. 



Arthur Eari.and, F. R. M.S. 

 Richard T. T.ewis, F.R.M.S. 

 Chas F. Rousselet, F.R.M.S. 

 D. J. Scoureield, F.Z.S., F.R.M.S. 



C. D. Soar, F.R.M.S 



DR. ERNST LEITZ. — We have much plea.sure in 

 announcing that the University of Marburg has conferred the 

 degree of Doctor of Philosophy 

 honoris causa upon the principal 

 of the optical works, Wetzlar. 

 We congratulate Dr. Ernst Leitz 

 on his well-deserved honour. 



A NEW MICROSCOPE 

 LAMP. — The lamp consists of a 

 five-inch circular base, having a 

 telescopic square vertical tube 

 about si.x inches long, formed of 

 two square tubes sprung so as to 

 slide the one within the other. 

 The outer tube is plugged at the 

 bottom with brass and terminates 

 in a three-eighths inch brass 

 screw, fitting into a hole tapped 

 in the base to receive it. This 

 is turned up square at the 

 bottom to ensure the upright 

 tube being truly vertical. The 

 inner tube is plug.ged at the top 

 and terminates in a square boss 

 bored and tapped (three-eighths of 

 an inch thread! brass on two faces, 

 butnot rightthrough — thetwo holes 

 communicating with each other 

 to pass gas, but not permitting gas 

 to go into the inner tube. One 

 face of the boss carries a one-and- 

 a-half inch length of three-eighths 

 inch tube having an ordinary three- 

 eighths inch burner elbow screwed 

 on to it. The other face has 

 screwed into it a wooden nipple 

 bearing a three-eighths inch 

 screw, and formed to take a 

 rubber tube. The nipple should 

 be of hard wood in order that 

 the heat of the lamp is not con- 

 ducted to the rubber tube. The 

 burner elbow projects downwards 

 with a male thread three-eighths 

 of an inch and takes an ordinary 

 bijou incandescent burner of from 



thirty-five to forty candle power. In place of an ordinary glass 

 shade, an opaque shade of one-and-three-quarter inches brass 

 tubing is constructed, cut to take a projecting window for 

 various light modifiers of glass three inches by one-and-a-half 

 inches. Three holes in the top of the shade to match screws in 

 the burner serve to attach it. The whole shade is chemically 

 blacked to keep back extraneous and unnecessary light. As 

 the ordinary lamp is seldom of more than four-and-a-half to five 

 candle power the gain in illumination is very great, and the 

 light being white instead of yellow, still further accentuates the 

 advantage. For dark ground and polariscopic illumination, 

 or that of opaque objects, the gain is enormous and. the 

 mesh of the mantle in these cases forming no disadvantage, 

 it can be reconmiended. It is not put forward for critical 

 illumination with high powers but for more general use, 

 where a brilliant rather than a critical light is desired. 



With the siUer side reflector the results are singularly 



bright and beautiful. As the gas does not traverse the 

 upright tubes, it can be used at any height either above or 

 below the stage. 



Chas. E. Heath. F.R.M.S. 



ROYAL MICROSCOPICAL SOCILTV.— December 21st, 

 1910, Mr. E. J. Spitta, L.R.C.P., vice-president, in the chair. 

 W. R. Traviss : .^ iviiall microscope lamp, particularly suited 

 for opaque objects and dark-ground illuniniation with high 

 powers. The light used was a small inverted incandescent 

 burner, carried at the extremity of a short arm. that could be 

 easily moved up and down on a standard. The hglit could be 

 brought \ery close to the table or raised to illuminate opaque 



objects on the stage. — M. J. Allen: 

 .^n easy method of treating 

 printing-out paper for all kinds of 

 photography. The author recom- 

 mends that the prints be washed 

 in a strong solution of salt, then 

 placed in a saturated solution of 

 hypo., after which they are to 

 be washed in running water. — 

 Chas. H. Higgins: A new system 

 of filing slides. — A. .^.C. E. Merlin: 

 On the measurement of Grayson's 

 new ten-band-plate. The plate, 

 comprising ten bands running from 

 inVuth to TurrMirth of an inch, 

 had been ruled by an improved 

 machine, and was found to be 

 much better even than Grayson's 

 earlier productions. The author 

 in measuring the bands used a 

 selected objective of 1-32 N.A., 

 having an initial magnification of 

 one-hundred-and-forty-three on a 

 ten-inch tube. A Nelson-Powell 

 screw-setting micrometer, which is 

 alone suitable for the purpose, 

 was used. The result obtained 

 was that the variation from the 

 mean in the spacing of the lines 

 did not exceed narrViTTj-inch. The 

 mean diameter of the lines was 

 •00002488-inch. The author also 

 made a series of measurements 

 with one-inch, half-inch, and 

 quarter-inch objectives, and came 

 to the important conclusion that 

 low powers were unsuited for 

 micrometry. — Jas. Murray: Some 

 African rotifers — Bdelloida of 

 tropical Africa. Thirty-three 

 species of Bdelloids were obtained 

 from dried moss, sent by Mr. A. 

 Allan and Sir Philip Brocklehurst, 

 from British East Africa. Nine 

 of the species are new to 

 science. Several of them have very distinct characters, not 

 previously noted for any Bdelloids. Habrutrocha caiidata 

 has a tail-like process, the function of which is unknown. 

 The animal secretes a protective shell, and the "tail" is 

 enclosed in a .slender tube, open at the end, so that the shell 

 has two openings. Habrotrocha acornis has no trace of 

 spurs, otherwise universal in the order. Several other species 

 approach it in this respect, having the spurs reduced to minute 

 papillae. Habrotrocha aiiriciilata, when feeding, has at 

 each side of the head a peculiar ring-like auricle, giving it the 

 appearance of a two-handled vase. The nature and function 

 of the auricles remain unknown. Their form, even, is difficult 

 to interpret, as they present apparently contradictory appear- 

 ances from different points of view. The Bdelloids take a 

 very important place in moss-faunas. In every country they 

 are abundant, and in most regions there is a fair proportion of 

 peculiar species. When more fully known, the Bdelloids seem 



Figure 1. 

 A New Microscope Lamp. 



