1883.] 



MICROSCOPICAL JOURNAL. 



139 



— Mr. Charles Coppock, who has re- 

 cently established himself in an elegant 

 store in Bond Street, London, has issued 

 his first catalogue of scientific instru- 

 ments, which is quite fully illustrated. 

 Mr. Coppock does not intend to confine 

 his business to selling microscopes of 

 any one make, but he proposes to furnish 

 any instruments that may be desired. We 

 notice in the catalogue a list of Tolles' 

 microscopes and objectives, Bulloch's 

 microscopes, and we understand that Mr. 

 Coppock has taken the agency for Spen- 

 cer's objectives. 



— Among the new accessory instruments 

 we notice an "objective-screw microm- 

 eter" which is for the purpose of measur- 

 ing objects too large to be seen in the 

 field at one view, and an ocular-mi- 

 crometer consisting of a plate of glass 

 with divisions ruled upon it placed in a 

 Ramsden ocular, with a graduated screw- 

 head. Two forms of the Abbe con- 

 denser are figured, and an ingenious 

 arrangement for illumination with mono- 

 chromatic hght, as well as a spectro- 

 polarizer. The last two instruments we 

 will more fully describe in a future article 

 in this Journal. 



— Mr. Thomas Curties, has called our 

 attention to some slides illustrating the 

 embryology and structure of minute marine 

 organisms, which are worthy of more than 

 a passing notice. They are prepared by 

 a new method, the details of which we 

 do not know, but the rotundity of form 

 and the living appearance are remarkably 

 well preserved. Among the slides we 

 have seen are eggs of fishes, and of Crus- 

 tacea, fishes only one day out of the egg, 

 minute Crustacea of various kinds pre- 

 served whole or in parts, and a few 

 vegetal preparations. All of these were 

 preserved with surprising perfection, and 

 we are thereby led to hope that even deli- 

 cate algas may yet be preserved in all 

 their beauty of form, if not in color. 

 These preparations can be obtained from 

 Mr. C. Baker, optician, of 244 High Hol- 

 born, London. 



— Mr. W. Miller finds that the micro- 

 phyte Leptothrix bieccalis, which has 

 been regarded by some as causing decay 

 of teeth, occurs in three distinct forms — 

 as coccus, bacillus and the spiral form. 

 This organism enters the teeth after 

 acids have dissolved the lime of the 

 enamel and dentine. The author as- 

 serts that a growth resembling Saccha- 



romyces mycodcrma sometimes perfo- 

 rates the enamel of sound teeth. The 

 active agents in the decay of teeth he re- 

 gards as bacilli and micrococci which 

 may be found deeply penetrating the sub- 

 stance of teeth undergoing decay, 



— Homogeneous immersion objectives 

 have had their day — at least in the hands 

 of one English microscopist. It seems 

 the gentleman to whom we refer took one 

 of those lenses home to try. He under- 

 stood that it was a good lens for resolu- 

 tions. He tried it, but soon returned it, 

 saying he would not have it in his house. 

 It^vould hardly resolve P. angulatum ! 

 But the worst of it was his sad experience 

 with the immersion fluid. Lavishly used, 

 it dissolved the varnish of his pretty 

 slides, and spoiled their beauty. It got 

 on his pocket-handkerchief and imparled 

 to it an odor of some essential oil that 

 stood by him for a week. The lens, and 

 all lenses of its class, received his most 

 unquahfied condemnation. 



— Messrs. Ross & Co., have at last suc- 

 ceeded in reducing the cost of manufact- 

 uring the new Wenham binocular prism 

 so that they are able to introduce it. Here- 

 tofore the difficulties in the way of mak- 

 ing it have been an obstacle which at one 

 time led them to give it up entirely. 

 Even now the price will be about three 

 guineas for each prism. This prism 

 we may remind the reader, is 

 for use with both high and low 

 power objectives. It fits in the same 

 place as the ordinary Wenham prism, and 

 takes in the entire field of view — not 

 dividing the field like the common prism, 

 but dividing the light like the prism in 

 Abbe's binocular ocular. The prisms are 

 are cut at three angles for tubes having 

 a divergence of 13, 14, and 15 degrees 

 respectively. 



— Although a pair of scissors is not 

 strictly a microscopic object, yet we have 

 seen several pairs that were probably not 

 made without a microscope. At the 

 show-rooms of the Messrs. Rogers, Cut- 

 lers to Her Majesty, in Sheffield, there 

 is a delicate balance under a glass case, 

 in one pan of which there are twelve 

 pairs of perfect scissors, which are over- 

 balanced by a half-grain weight on the 

 other side. 



ERRATA. 



By a typographical error in the June issue, the name 

 of Mr. J. F. Hazlewood was used instead of Mr. T. F. 

 Hazlewood, as writer of the article on " Histological 

 Work." 



