♦ KNOWLEDGE 



lived a month or tu^ .hi .i -im':, ■,..,;:,!■, ,ii,i \. |-;. ij. 

 Should not care to ail- ■. : i i, ,. ■ i ; , ; : :i nfheat 



without experimental i -ii , .vhcre 



Thanksfor list of en.L:,. il n. i , - , ,,,■ , i:,,.(iiice 



word). It was not 1 -.,; i.,i ..;; ;,.i „,aLUi ..i a L..iu.i a.iijlit be 



put into a cocked hat. I du not know thu capacity of a cuckecl hat, 

 or believe comets to be so utterly insignificant anyway. From 

 experiments made by Prof. Wright, of Yale, it appears probable that 

 finely-divided cosmical dust in vacuo would be rendered incan- 

 descent, and in part vapourised.— W. Aston. I believe no such 

 works exist. But for reference I may mention the edition of the 

 " Encyc. Brit." preceding the present.— W. C. T. You deem me 

 more altruistic than I am. Knowledge has changed in form 

 chiefly because I could not longer stand the burden. My time and 

 work since Knowledge started were simply ffii-en ,nra;/. Com- 

 puting at the average value of my time to myself, I find" the gift 

 was a large one. I could afEord to make it no longer.— Omega. 1 

 am away from books of reference, and am unable to give you the 

 ftle of any book of logarithms giving what you require.— 

 A COEBESPONDENT (whose initials liave unfortunatelv been torn 

 off MS.) asks whether Dr. Ball's or Mr. Lockyer'.s astronomy is the 

 more trustworthy. I have seen no edition of the latter v\-ork 

 except the first, which was full of blunders (used for the supply of 

 awful examples at Cambridge), and the American edition, which 

 has been carefully corrected. Anything Dr. Ball writes may be 

 regarded as thoroughly trustworthy. Or course he makes mistakes 

 as we all do ; but not from insufficient knowledge or power. — 

 C. Caeus Wilson. I should attribute the red sunsets to meteor 

 dust. As regards thunderbolts, &c., I imagine that though electrical 

 phenomena may often accompany the downfall of a large 

 meteorite, no mass could possibly fall like a meteorite because of 

 electrical disturbance.— J. L. Polack. You ask why do we deal 

 with the 2/9 of 4/11 before the 3/5 H- 2/9, when considering the 

 expression 3/5 -i- 2/9 of 4/11. If you were told you were to receive 

 3/5 of a certain sum, and also 2/9 of 4/11 of the sum, would you 

 begin to determine your share by adding 3/5 to 2/9 ? 'What earthly 

 meaning would such a process have? You would first find 

 what 3/5 of the sum amounted to, then what 2/9 of 4/11 of the 

 sum amounted to, and then you would add the amounts together.— 

 G. E. In about four hours I could give you about as much advice as 

 you require. It would probably be all wrong, as I have no means of 

 knowing your aptitude for the study on which you propose to enter. 

 On the whole, it will be better to suppose your letter received a few 

 weeks later, when no earthly power will persuade me to answer a 

 question in Knowledge. — N. E. B. Thanks for the curious 

 example of mental inequality. Possibly Guillemin's "Heavens," 

 translated by Mrs. Lockyer, edited by Mr. Lockyer, and corrected 

 by myself, might suit you. You are quite right about books 

 of anuntrustworthy sort being read as if by authorities. Glad to have 

 made that ruddy eclipse matter clear. There was a curious example 

 there of mental inequality, for that writer cannot even now see what is 

 clear to many who have not half his acquaintance with some scientific 

 matters. But such slips are unfortunate. As you for instance, in 

 botany, your special subject, see blunders at once and want to 

 know whether books on other subjects are as untrustworthy, so 

 may many feel in studying papers on other subjects in which a 

 writer is supposed to be proficient, after seeing that such a writer 

 may have been very positive and even dogmatic when altogether in 

 error. For that reason I regard the correction and ready admission 

 of error as the sacred duty of a teacher of science. It" is also, like 

 honesty, good policy ; but that is a mere accident of the position.— 

 •T. Russell, C, Qy.^ Qy'. That quotation was marred altogether not 

 a little : by that printer'sdevil, or (which is the same thing) that devil 

 of a printer : not identified, so this is not personal. Would like well to 

 lecture at Kingsbridge ; but do not know how it may be managed. — 

 Jas. Mbbedith, K. T. M., Constant Subscribeb, J. M. Allen, 

 Albert Howell, L. Means, Wbamed One, Thos. Svnington, 

 and others Glad to find the proposed curtailment of correspond- 

 ence meets your views.— G. Hailey. Apply to publishers.— J. 

 BOEBODAILE. Oh why do you send us such nonsense? Abuse 

 science to your's heart's content ; but post your packet of nonsense 

 in a pump, or a stove, or in any chance opening in a quarry. You 

 will get just as much relief, and no one else will be troubled. — 

 COMMENTATOE. That must have been the acting editor, for I 

 never read such a paper.— Jas. Fraser, Jun.— One is an altera- 

 tion of direction, the other of distance. Deflect a telescope through a 

 very small angle, and it will bear on a widely different point on the 

 horizon; but shift it ten feet, keeping its direction unchanged, 

 and no appreciable efltect will be produced.— X. Ah ! You think 

 any nonsense, even the rubbish written bv Parallax, a Lady Matlip- 

 matician, John Hampden, and other foolish persons, might lie 

 written by any one who is an admirer of Herbert Spencer. Interest- 

 ing information truly ! Possibly you do not know what nonsense 

 those three Iiave written. The middle one in particular was a 

 twaddler "of the first water," having little claim to cither half of 

 her assumed name. 



(^iir Jnbrntors* Column. 



fCe give here, week by week, a terse description of such of the many 

 inventions as we think may be of use to our readers. Where it 

 is possible, the number of the patent is quoted, to enable those 

 who desire fuller information to procure the specification from the 

 Patent Office in Cursitor-street, Chancery-lane. We shall, generally 



speaking, confine ourselves 

 often happens that an article comes under o 

 although not quite novel, is worthy of mentii 

 and ingenuity. In such a case we should not 

 our readers to it. And while we thus increo 



ir pages 



! the s 



! the 



iventions; but H 

 e which, 

 s utility 



being a popular 

 rade journaU, 



THE COMBINATION EASEL DESK. 



This desk, introduced by DaM.l r:,ii:,, ,. ii,, Small Heath, 

 Birmingham, is the result of" car. f, I : :< i|uirements of 



an art-student. It is very light, -ii ■: i art, there being 



no complicated machinery of any ,..;,, ,, ,. It is rendered 



equally applicable for drawing, paint. i.y, ul,.;, -a.^delling, or writing 

 by the raising and adjustment of the desk toji. 



The top of the desk is hung with hinges upon the front side, and 

 is adjusted to any desired slope by means of a toothed rack. On 

 the front edge of the desk top is a movable ledge, consisting of a 

 bar of metal in which are slots of an [_ shape, through which pins 

 are made to pass, and by which it is fixed to the top. This ledge 

 forms a rest for the dravring-board, canvas, or cast, whilst, when 

 not required for that purpose, it can, by means of the vertical and 

 longitudinal slots be depressed below the level of the desk-top, 

 leaving the top free from projection for writing purposes. A movable 

 and adjustable light metal frame, for holding copies, objects, casts, 

 &c., is fixed to the back part of tlie desk-top, and is so constructed 

 that it may be adjusted to any inclination to the desk-top, or, for con- 

 venience, be lowered down behind it out of the way. This is effected by 

 means of a slot, pin, axle, and quadrant rack, so that by lifting the 

 whole rail the length of the slot the student is enabled to place the 

 copy or cast in the best position for work. One advantage of this 

 frame is that the object to be copied, whether drawing or cast, is 

 not foreshortened, but can always be kept at right angles to the 

 student's eye. On the left-hand side of the desk is provided a space 

 for the reception of drawing-boards when not in use, and also a 

 receptacle for pencils, instruments. Sec. There is also a water-pot 

 for colouring purposes, carried in a fixed or swinging bracket, and 

 fixed to one of the legs, or on the side rail of the desk, according to 

 choice, and a hole is left in the desk-top at the back and on the 

 right-hand side for the reception of this pot, so that it may be used 

 when the desk-top is not inclined. The desk is said to be fast 

 gaining popularity in the Mi.Uands, for its simplicity and 

 practical adaptability to tlie requirements of an art student. 



PORTABLE C.UIERA STAND. 

 Mb. Asheoed has patented a portable camera stand, in which 

 each leg is composed of three pieces ; one forming, when ex- 

 tended, the bottom half of the leg slides between the other two 

 pieces. On the inner sides of the pieces which form the upper half 

 of leg grooves are cut dovetail in shape, and on each side of the 

 sliding piece are corresponding pieces to fit in these grooves. Two 

 brass dips fasten together the lower end of the upper half of stand, 

 and a brass screw with milled nut passes through the upper end to 

 fasten the leg to the head. Across the upper end of sliding piece 

 are cut two grooves, one on each side, about an inch wide; into these 

 grooves are fitted two cheeks which extend across the sliding piece 

 on to the two pieces which form the upper half of leg. Right 

 tlirough these (the sliding piece and cheeks) is passed a brass screw 

 with milled head, and at the back is fastened the nut. By merely 

 loosening this screw the sliding part may be moved freely up and 

 ■■ again be fastened in any required positioi "" - 



head is made trianguli 

 ears, the width of which 

 Across these ears grooves 

 Underneath the head an 

 so tliat when the metal 



lape, and has three hollow projecting 

 responds with the sliding part of leg. 

 cut to fit the screws in top part of leg. 

 ross tliese grooves are placed springs, 

 I in top end of legs are pushed along 

 safely by the springs until released. 

 The advantages claimed for this stand are its firmness, portability, 

 the facility with which it is set up and taken down, simplicity of 

 manipulation, and the fact that having a long slide, it can be 

 used on the side of a hill or on any uneven ground as easily as on 

 the flat. 



