♦ KNO^A^LEDGE ♦ 



[Sept. \b, 1882. 



1 i-aimot imagine now.— C. L. Cane. Your letter sent to printers, 

 but may be delayeil -eij;lit or uiue pages of letters waiting. 

 ^J. E. UrosoN. What is there to explain? It is pretty 

 obvious that if you buy 30 omnges at two for a Id., and 30 

 •t three for a Id., you pay 25d. ; while if you sell the lot 

 at two for 2d., you get only 2 W., or lose Id. If you mean 

 that one could ex|>eet anteeedently neither loss nor gain, I would 

 invite vou to notice that by taking 10 sets of 20 oranges from the 

 first lot, and combining with 10 sets of 3, made up out of the 

 second lot. yon can make up 10 seta of 5, for each of which you 

 paid 2d. There rvmain 10 oranges of the first lot, for which you 

 paid 5d. If now yon sell these for 4d., yon are antecedently likely 

 to h«o a penny by the transaction. If there had been 20 at 2 a 

 penny, and 30 at 3 a penny, the 50 might have been sold at 5 a 

 penny, with neither loss nor gain. Such proportions should always 

 hold to imtke the bargain sound. — Tinbeki. Pray excuse long 

 deUy in thanking you for sample of Persian tobacco. I wanted 

 your letter to Bp|>ear long since. — A writer with hieroglyphic sig- 

 nature asks nine questions, most of which are such as only advanced 

 students of astronomy would take interest in, and thcu would know 

 the answers. Among the rest, occurs this question, " Is there any 

 way to do subtraction and addition by logarithms ? " Why, certainly. 

 Thus, suppose yon wish to subtract 2 from 7. Double the logarithms 

 of "and 2, and find of what numbers the results thus obtained are the 

 logarithms. Divide the difterenceof these numbers by the sum of 7 and 



2 ; the quotient mil be what you want. Some prefer to subtract 2 

 directly from 7. — Epsilo.v, who will soon be a Durham B.A., wishes to 

 know the best means of becoming a surgeon in the least possible time. 

 He lives near a good medical school at Owen's College, Manchester. 

 — J. W. liiMirnBoYn. Would insert your interesting letter 'if not 

 overcrowded. It seems to me the good effect of exercise you 

 mention arises from the stimulus to the circulation. Quite agree 

 with you alx)ut the pleasant effect of a single glass of wino when 

 mind is ilij ressed or bixly wearied. Ucware, however; it is a deadly 

 poison ; that single glass, perhaps once or twice a week, is absolutely 

 certain to kill yon in less than a century. — M. M. Williamson. 

 Would return the letter on Blasphemy, but fear it was not pro- 

 served. 



ASTRONOMICAL. 



B. M., F. N. C. R.— " F.R.C.S." promises ns to look at Z Cancri 

 and Stmve 175 (Bird's Star near Castor) as soon as they come into 

 .•I rather more favourable position. Just now it is between 3 and 

 ■ .i.m. before either of them is 30' high. 



CHEMICAL. 

 Kelt. — For the Advanced Stage in Inorganic Chemistry, Science 

 and Art Department, the following works may bo studied : — 

 Theoretical, Rosooe's "Elementary Chemistry," for Practical 

 Analysis ; laeo's " Inorganic Chemistry," published by Longmans <t 

 Co. The latter also gives a considerable portion of the theoretical 

 dirisionof the subject. (Answers to two other querists were inserted 

 in No. 3<;, under the heading "Cekto.")— Iota. 1. The flame 

 from a Itun»4>n burner if hotter when air is mixed with the gas tlian 

 when the gn.s is simply burnt in air, because the more intimate 

 mixture of oxygen gas (a constituent of air) with the coal gas 

 (comixiHod of hydrogen and carbon) produces a much more 

 complete state of oxidation or combustion. 



BOTAXICAL. 

 K. C. H. (Worthing). — Perhaps my explanation of the difference 

 between t'ernniums and [lelargoniumg was a little too condensed. 

 All fK-largoniuma have one sepal with n spur, the spur being com- 

 bined with the flowcr-stnlk or pedicle. The best way to under- 

 stand th'ir structure is tirst to take a common nasturtium or Indian 

 creM (Tr'-jnrolum nuijwi) and liend back its spur till it touches the 

 stalk. Now, imagine the two firmly grown together, and you have 

 exactly the arrangement of the pelargonium. There are always 

 two 7ietalii more or lens unlike the other three ; at the base of these 

 and l»-twt<n them lies the hollow tube or spur— the "small deep 

 liole " which yon mention. Thiii runs along the flower-stalk as far 

 aa the little prfdulK^rance, where the honey is secreted. If you cnt 

 acrms the ttalk with a ri^n-knifein successive slices you can readily 

 follow up the tul)0 t'j this jKjint. A little examination will show yon 

 how the part« of the flower are spccinlisi.'d for fertilization by the 

 but'- rfr . -*IM. iri»/rt II.. Ir I..i.i.' pnAnmcPH into the tube. Observe 

 •-; 'I'irity first.nndafterthey have 



>■''■' ' - five rays and turns upward so 



' iiiHeet which brings it jKillen 



'•' !■ you mention as to the leaves 



is q'li'- ui.;.,iin.l.<l. .< V. I! (MiimUiwn). Cap<!r spurge (K«- 

 jiJiortia lalh'jrit) it acrid and poisonous. I did not know Ijcforo 

 tl>M it prfiduced an eruption ; but if yon happened to have any 



slight cnt on your lingers, some of the poisonous juice might easily 

 have got into your blood. The plant derives its very mfsloading 

 name from the .fact that its capsules slightly resemble capers; but 

 many people have bcou more or less poisoned by rashly concluding 

 that'they could ]>icklo and eat thorn with impunity. 



GEOLOGICAL. 

 Fli.nt-Jack. I notice that no rejily has yet lieen given to the 

 query as to the time and place of the death (if lie be dead f) of tho 

 celebrated fabricator of stone implements and other spurious an- 

 tiquities, whose great misfortune it was to be born about five 

 thousand years too late. When I became Curator of tho Leicester 

 Museum, in 1872, I found that the institution possessed severnl 

 specimens of his handiwork ; but a knowledge of his abilities had 

 by this time become widely disseminated, and it is a fact that ho 

 was only able to sell somo really good examples of neolithic Hints 

 by offering them as his own workmanshi|i ! During tho no.\t two 

 or three years he was frequently an inmate of tho Leicester work- 

 house. About this time 1 carefully watched his mode of chipping 

 flint, and certainly his dexterity in manipulating that refractory 

 substance was very great. After breaking a flint nodule in 

 half with a heavy hammer, he would select a portion, and 

 by smart blows delivered from tho elbow, detach long, knifo- 

 liko flakes, guiding and lengthening tho fracture by tho 

 pressure of liis fingers. Tho flakes so obtained ho would 

 fashion into knives, saws, <tc., by rapid up and down blows 

 of a thin iron rod, bent at one end. 1 often tried to induce him to 

 attempt the imitation of some of tho wonderful Danish daggers or 

 spear-heads, made out of Hint, yet not much thicker than card- 

 board, and having surfaces rippled in the most beautiful manner, 

 Over these he always shook his head and repeated again and again. 

 " 'tis a harbariniis art, lost to mankind ! " One day, I think it was 

 the autumn of 1875, ho came to the Museum in unwonted alarm, 

 and announced his intention of making an early departure, for 

 " they were dying off like flies at tho workhouse, and ho would 

 sooner die in a ditch." This was the last I saw of Edward Simp- 

 son; irreclaimable scamp and true tramp though he was, I cannot 

 help a kindly feeling for him, and 1 should bo glad to learn, with 

 your querist, where and liow his wanderings wore ended. — W. 

 Jekome Haurisun. 



TKICYCLING. 



Mb. Litciikord. — I had had my attention drawn to the mistaKo 

 in my article. It was by a slip of tho pen that I described tho 

 " Ilumber" asa rear-steerer — of course it steers in a similar manner 

 to a bicycle, by the movement of the front wheels. The truth is 

 that I had in my mind the title of my article on tho form of the 

 tricycle, and your correspondent will see that in tho case of tho 

 "Humber" there arc two large wheels in tho front and one small 

 wheel behind. Possibly rear-steering machines may not prove well 

 fitted for riding at tho very highest or, in other words, racing 

 speed. But I doubt if this would materially affect their sale. 

 When, as Mr. Litchford states, the rear-steerer was found un- 

 steady, both liimself and his fellow-competitor were probably 

 going at between twelve and fifteen miles an hour. Very 

 few tricyclists care to ride faster than from eight to 

 ton miles an hour, and at this rate of speed most of tho rear 

 steerers I have tried have been fairly steady, thiiugh they might 

 have been improved in this respect by having the pedals brought 

 underneath tho rider, and the backbone lengtljeneil in the manner 

 1 have indicated in my previous article. I think it quite possible 

 that the greater number of tricycles will, for ilii. future, bo made 



of the front-steering type. For ii ulri who purohaso 



a machine and wish to ride at -m practice, a 



front steerer will bo best, bin i i i i Imii tliat the 

 rear-steering machine need ncciH ;iji1; I- m air. My prin- 

 cipal object in writing my article w:is to point out that 

 the ba<l re|)utation this class of machine lias acquired has 

 been due to errors in constniction. Last year I had an ugly 

 accident myself while riding a " Salvo," which I believe to bo 

 the safest of all front-steering machines. In this experience I am 

 not alone. A well-known and excellent rider turned more than ono 

 somersault, when running down hill on a " Salvo" a few weeks since. 

 This year I have ridden only roar-steorers, without any apjjroachto 

 an accident. Of course, I have ridden carefully when descending 

 steep or very rough hills. Your correspondent is mistaken in sup- 

 posing that tho hill-olimbing power of the " Monarch " is duo 

 entirely to the small size of tho wheels and long cninks. In my 

 " Monarch" tho cranks have but 4J in. throw, while the " Premier" 

 I have has cranks with nearly GJ in. throw. Many riders besides 

 njyBolf will be sorry if manufacturers generally give up making 

 rear-steering tricycles. I am looking forward to tho " Sterling," 

 with its novel application of back-pedalling, being made one of tho 

 best machines of the day.— Joii.v BuowM.NO, L.T.C. 



