60 



♦ KNO^A^LEDGE - 



[January 1, 1887. 



with a coarse woollen clotb." It is said that a coat wUl last 

 six months.* 



Of preservative media, adapted to the floor of the labora- 

 tory, the two under-mentioned ai-e worthy of trial : — 

 1 . " Mix together boiled linseed oil and finely powdered 

 coal, to produce a substance of the consistency of paint. 

 Apply a coat of this to the floor." 2. " A mixture is made 

 in a metal pot of 40 parts of chalk, .50 resin, 4 linseed oil, 

 and 1 part of native cuprous oxide. One part of sulphuric 

 acid is cautiously stirred in. A sort of mastic results, 

 which may be applied hot, and when dry forms a vai-nish 

 hard as stone." t 



In spite of every care, however, dust will creep into the 

 laboratory, from our clothing, boots, the wear and tear of 

 furniture and instruments, books, fireplaces, and lamps. 

 But when all the precautions noted above are carefully 

 observed, it will be found that occasional wiping with a rag 

 leaves the room practically clean and comfortable : and the 

 student will then be able to indulge in delicate dissecting 

 with the microscope and elaborate mounting of objects, 

 without any fear of danger from floating dirt, and with 

 a rapidity which would be impossible under any other 

 circumstances. 



Under the name of the " Dust Inhaler," a very ingenious 

 contrivance has been devised and patented by a Mr. 

 Newton, whose specification is thus given : — " A horizontal 

 fan suspended and revolved in a hollow cone over a tray of 

 water, creating a partial vacuum in a small cylinder above 

 the fan, from which, and connected to it, an elastic tube of 

 any length, with a revoh-ing hair or other brush at the end 

 of the same, so that the brush loosens the dust, and the 

 cui-rent of air entering the partially-exhausted tube carries 

 the dust with it through the fan, and impinges on the 

 surface of the water ; the air then passes through perfora- 

 tions free of dust." | The apparatus is useful for sweeping 

 floors, carpets, footpaths, (fee. ; to dust walls, curtains, and 

 clothing; and, as it proceeds, collects the dust to deposit in 

 the tray of water : hence its value in the laboratory cannot 

 be over estimated. 



LABORATORY FURNITURE. 



The subject of laboratory furniture has received but a 

 modicum of attention in this country, although our Con- 

 tinental neighbours, and especially the Germans, have 

 made vast strides in this direction. The poor naturalist is 

 not even so fortunate as his chemical brother in this 

 respect, for whilst the latter can procure ready-made 

 furniture suited to his requirements, the former is invari- 

 ably compelled to make shift with what he can borrow 

 from various quarters — the kitchen, bedroom, and other 

 domestic sources — or is obliged to call in the aid of an 

 architect or carpenter to design and produce articles upon 

 the spur of the moment which are afterwards found to be 

 wanting in many essential details when they come to be 

 tested in the severe school of " mother experience." In 

 this way it often happens that articles of the most hetero- 

 geneous assortment find their way into hrs sanctum, and 

 give it more the character of a lumber-room than a well- 

 regulated workshop ; these remai-ks extended, it is to be 

 deplored, are, with but slight modifi&itions, equally applicable 

 to biological and geological laboratories in even some of 

 our modern universities and colleges. But chairs and tables, 

 cupboards and book-shelves, &c., do not constitute the sum 

 of all that is required for the adequate equipment of the 



apartment ; there are also I'eagent stands and bottles of 

 suitable shapes and sizes ; vats and jars for decayable 

 specimens : boxes and cabinets for minerals, rocks, and 

 dry matei'ials ; aquaria for plants and animals ; a hot and 

 cold-water supply ; and rational wearing apparel for the 

 worker ; all of which call for description in this place rather 

 than amongst the instruments that are directly employed by 

 the student to assist him in his researches. 



SOLUTION OF PUZZLES. 



UZZLE XIII. It is required to divide abcd, 

 Ji'(/. 8, bi/ straight cuts into four parts, vyhicli 

 shall Jit in «flk {fiy. 9), a pctralleloyram 

 having the angle a equal to the angle A, and 

 its sides av, «K in a given proportion, by the 

 first of the turn methods employed for rectangles 

 in the last number. 

 In AB bxke E (fig. 11), so that ad : ae : : aK : ap. On ab 

 (towards dc) describe the circular arc afb to contain an 



* The Illustrated Science Monthly, London, March 1885, vol. iii., 

 p. 95. 



t Ihi'/.. August 1885, vol. iii., p. 254. 



I Patent Office Register, No. 14,050, a.d. 1884. ■ 



Fig 8 



angle afb equal to the angle adc. (Complete the circle, for 

 future purpose, by the arc af'b containing an angle equal 

 to the angle dab.) Through e draw the chord fef' parallel 

 to ad; draw fb cutting DC in h ; and take fl equal to hb. 

 Complete the parallelogram aklf. Then I leave it to the 

 student to show by similar triangles aef, fab ; and by the 

 proportion da : ae : : an : av (fig. 9), that aklf is in all 

 respects equal to rdvLF. It will also be easy for him to see 



r Fig. 9. "^ 



that if KM is drawn parallel to ad, the spaces numbered 

 1, 2, 3, 4 in ABCD are in all respects equal to the spaces 

 similarly numbered in aklf. 



Thus ABCD is divided as required. 



Puzzle XIV. — To do the like bi/ the second method em- 

 ployed for rectangles in, the last number. 



Part of the construction is shown in fig. 11, af being the 

 shorter side of the rectangle required. We complete the 

 parallelogram aklf as in fig. 12 ; take bg equal to fl, and 



FislO- 



draw the parallels jg, car, cutting off also the small triangle 

 ghk equal to jfg in all respects. Then the parts of abcd, 

 numbered 1, 2, .3, 4, are in all respects equal to the parts 

 similarly numbered in aklf. 



Note. Remarks similar to those made in regard to the 

 division of rectangles apply also to the division of these 



