HARDWICKE'S SCIENCE-GOSSIP. 



39 



Thus saying he's well pleased to rest his case in 

 The physical condition of the ocean basin. 

 But Ball, with vision cl^ear as light of lime, 

 A-glimpsing down the Corridors of Time, 

 Sees what no scoffers ever may deride, 

 That is, he sees six hundred feet of tide ! 

 Oh, what a sight to make the sea-sick ill, 

 Oh, what a power existed in this mill 

 To plane the earth and cut off mountain-tops. 

 Or get in geologic time with skips and hops. 

 This Hull most quickly sees and thus explains 

 The denudat ion of his sea-like plains. 



Thus moonstruck do these " swells " of science raise 

 A chorus loud and long to Darwin's praise ; 

 But fear fell on his soul, and in defence. 

 He disclaims all their mighty inference. 



A Conifer. 



MICROSCOPY. 



Drawing, &c., from the Microscope.— In re- 

 ference to the valuable paper by E. T. D. on 

 " Drawings and Paintings from the Microscope," in 

 the January number, will you allow me to suggest 

 what I think a preferable material to cardboard or 

 paper, especially if the drawings are made of the size 

 he mentions. If pieces of finely smoothed glass are 

 obtained, it is as easy to draw or paint upon or sketch 

 outlines upon with camera lucida as it is upon paper. 

 Every detail possible in the one case is possible in 

 the other, and it may be rendered a work of art in 

 every sense just as easily. In fact, the amount of 

 finish is only limited by the skill of the painter or 

 draughtsman. Such drawings can be coated with 

 varnish or have another piece of glass cemented upon 

 them with Canada balsam ; if transparent colours have 

 been used the drawings can be thrown upon the screen 

 or on a white wall by the lantern, and thus be viewed 

 in all their beauty (but greatly enlarged proportion) 

 by a large number of spectators at once. Beautiful 

 pencil drawings can be made in the same manner and 

 coloured to any required extent, and if it be desired 

 to alter, the drawing can be partially or, if necessarv', 

 wholly removed without deterioration of the surface 

 upon which it is made. A background of white 

 paper is all that is necessary to enable us to look at 

 such transparent paintings or drawings as ordinary 

 paintings. This method of preparing illustrations of 

 microscopical objects was originally described in the 

 Monthly Microscopical Journal oiY€bTM2Lty 1874, by 

 the Rev. Mr. Dallinger, who has made more than a 

 thousand of them to illustrate his lectures. It is un- 

 necessary to add that his representations are perfect. 

 Even to illustrate an ordinary paper this method 

 possesses an advantage over every other, which I will 

 not occupy space in referring to, but merely mention 

 one which I can confirm from practice myself — that 



very indifferent skill will produce tolerably satisfac- 

 tory transparencies for the lantern, and suffice to 

 convert an otherwise uninteresting paper into an 

 attractive one. E. T. D. omitted to notice that out- 

 lines produced by camera lucida are reversed. This- 

 introduces a little difficulty when filling up from the 

 microscope. The slide can be turned over with low 

 powers while outlining, but this cannot be done with 

 a high power. — Edwin Holmes. 



"The Micrographic Dictionary." — We have 

 received all the parts up to and including Part VII. 

 of the fourth edition of this invaluable work, brought 

 up so as to include the most recent microscopical 

 researches. 



Mounting for Hot Countries.— I should be 

 greatly obliged if any of your readers, who may have 

 had experience in mounting in Canada balsam and 

 dammar varnish in India, would give me a few hints 

 on the subject, (i) I find that the following method 

 succeeds better out here than any other. Centre the 

 object on the slide, drop on it the requisite quantity 

 of balsam, and then transfer it to the air-pump for a 

 quarter of an hour or twenty minutes. Any air 

 confined in the object or the balsam is thus brought 

 to the surface, and the resin finds its way into the- 

 vacated air-spaces. On removing the slide from the 

 air-pump I heat it till the balsam becomes glassy 

 (and just short of boiling) and this generally causes 

 the bubbles brought out under the receiver to flow to 

 one side. "Whether mounted in this way or without 

 the air-pump, at least four, sometimes six, weeks 

 elapse before the balsam sets. Is the delay due to 

 climatal influences, or to some error in my process ? 

 Can the setting of the balsam be safely expedited in. 

 any way ? (2) There is at least as much delay when 

 I use chloroform and balsam. I had my solution 

 prepared by the first chemists here, and instructed 

 them to evaporate the balsam to glassiness before 

 adding the chloroform. In the majority of cases the 

 mount becomes slightly milky, and a power of sixty 

 diameters shows the presence of mitiute particles,^ 

 which close and continued observation proves fall 

 with the slope of the stage, and this even in the case- 

 of objects that have been mounted for over six 

 months. My objectives are not sufficiently powerful 

 (310 diameters being my highest) to enable me to- 

 determine what this foreign matter is. I conclude it 

 is condensed vapour, and not air, from Ws, falling. A 

 damp wind, as from an open window in our "rainy 

 season," blowing on the chloro-balsam produces a 

 scum and increases the number of particles. Heating 

 as recommended in the text-books, dispels the 

 cloudiness for the time, but some of it returns when, 

 the slide has cooled, or after the lapse of a few days. 

 What is the cause of these failures, and how can they 

 be obviated ? (3) In using dammar varnish I meet 

 with as much disappointment. I got my varnish out 

 from Messrs. C. Baker & Co., and I have no doubt 



