Jax. 6, 1882.] 



♦ KNOWLEDGE ♦ 



211 



[154] — Fbocs. — Why are frogs excluded from the class Reptilia ? 

 — H. J. C. W. — [We always supposed that the class Reptilia 

 included the Amphilia, and that frogs were classed as Batrachian 

 Amphibia. — Ed.] 



[155] — ToETOiSES. — Wliat is the average duration of life of the 

 tortoise, and how long can they remain under the earth ? — 

 H. J. C. W. 



[156] — WoKMs. — How is it that when a worm is severed in two, 

 its parts still show signs of activity ? — H. J. C. W. — [If you 

 consider the nature of the nervous system in worms (and all 

 articulated animals) that a double chain of ganglia, one may 

 almost say of brains, runs along the body, you vaU see that the 

 phenomenon is natural enough. — Ed.] 



[157] — An-MUMM. — The characteristic ingredient of common 

 clay — what is the present process of obtaining this metal, or is 

 there a treatise published on its extraction ? Will any one of the 

 metallurgists of Knowledge kindly furnish the information to one 

 who believes that (by a new process) the price of aluminum might 

 be reduced to that of copper ? — Luna. 



[158] — A 1 lb. weight is carried to the top of a tower. Would 

 this, if allowed to fall, raise another 1 lb. from the ground ? They 

 are connected by a thread passing over a pulley. Xeglect, of 

 course, the weight of thread, and assume it to be perfectly flexible 

 and to move without friction. — H. Rolfe. — [" H. Rolfe " should read 

 a description of Atwood's machine. The weights would not move 

 aniess some impulse were communicated to one or other. Such an 

 impulse downwards on the upper weight would cause uniform 

 motion of both weights, until the one which had been uppermost 

 reached the ground. — Ed.] 



[160] — Botany. — Can any one tell me who was the author of 

 " The British Garden," a descriptive catalogue of hardy plants, 

 indigenous or cultivated, in Great Britain, with Latin and English 

 naines ? Two vols., published by S. Hazard, of Bath, 1799. — 



El-PTKBIS. 



[161] — Heat fbom the Stars. — Does the earth receive an appre- 

 ciable, or any amount of heat from the stars ? — Stcdent. [From 

 measm-ements of the heat of a few bright stars and comparissn 

 with heat received from sun, as also of light of star with light from 

 sun, the inference seems sound that the total heat received from 

 stars, bears to solai- heat something like the same proportion that 

 tlie light received from all the stars bears to the sun's light. — Ed.] 



^fplifsi to ©unirs. 



[79] — Mental Phtsiology. — As " S. S. S. S." seems anxious to 

 test the accuracy of my information concerning Mr. Cvples's book, 

 1 can only tell him how it came under my notice, which was by 

 press reviews, particularly one from Prof. Groom Robertson's organ. 

 Mind, which carried conviction to my mind that a ver^- unique and 

 able work on the subject was referred to. I at once obtained it, 

 and (as stated before) on the menial side, and as being exactly in 

 keeping with its title, have never had any regret in so having pur- 

 chased it. It would be out of place here to say further. If he 

 wont to Strahan's and asked to see the book, he might get a little 

 idea thus of its character, &c. — S. 



[125]. — It is possible to prepare indigo on the large scale, but, 

 unfortunately, not profitably. The well-kno^vn German chemical 

 factory at Baden succeeded in producing artificial indigo, which 

 made its appearance in the market as a commercial article, but it 

 was announced in the newspapers a week or two ago that operations 

 have been discontinued, as at present it cannot be made to pay. — 

 H. Gbimshaw. 



[136] — Sunlight on Fire. — The draught of a fire depends in 

 great measure on difference of temperature between air in chimney 

 and air in room. Sunlight, by heating' the air round a fire, tends to 

 create a draught in wrong direction. A smoker's draught, being 

 created by the lungs, does not seem a parallel case. — C. T. B. 



[71] — X.iSTES OF Flowers. — Haj-ward's " Botanist's Pocket- 

 Book," 4s. Cd. (Bell & Sons), gives both scientific and common 

 names, with concise characteristics. Dr. Hooker's "' Student's 

 Flora," 10s. 6d. (Macmillan), though giving fuller particulars than 

 any other handbook, contains comparatively few common names. 

 Bentham's "British Flora," 12s. (Reeve & Co.), contains many 

 common names and a complete " English scientific nomenclature," 

 also outlines of botany. &c. ; but it includes fewer species and 

 varieties than either Havward's or Hooker's. — Eupteris. 



[80] — The Chin. — ■■ Ethnologist's " observations are not in 

 accordance with the remarks of Lavater, who says that " flatness 

 of chin bespeaks the cold and ilrj- ; smallness, fear ; and roundness. 

 with a dimple, benevolence." Elsewhere, he adds: — "A long 



broad, thick chin — I speak of the bony chin — is only found in rude, 

 harsh, proud, and violent persons. — Eupteris. 



[90] — The Magnetic Needle. — I believe it is considered that a 

 current of electricity is constantly passing round the earth from 

 east to west, causing the magnetic needle to point north and south. 

 Similarly, a wire from a battery, passing over or under the needle, 

 will make it stand at right angles to the current. — Eupteris. 



[105] — "J. S." can obtain all the information he requires from 

 Mr. James English, naturalist, of Epping village, who is to bo 

 congratulated as the discoverer of a very ingenious, and, I believe, 

 the only sure process of preserving fungi and lichens, and not only 

 these, for in his hands even flowers of the most delicate structure 

 and hue retainjall the grace of form and richness of colour provided 

 by nature. Having myself seen many remarkably perfect and 

 beautiful examples of Mr. English's work on both fungi and flowers, 

 I can recommend (as it gives me much pleasure to do) your corre- 

 spondent and others interested in this really valuable discovery to 

 communicate with him. In consequence of the great success of the 

 method, and the largo demand following upon it, I understand Mr. 

 English is engaged upon publishing it in full — a generous act for the 

 benefit of the world at large — and the subscription-list is open to any 

 wishing to obtain a copy of his book. It only remains for me to add 

 that, personally, I am entirely disinterested in the production, and 

 offer this information as well for the profit of those botanists who 

 are as yet unacquainted with this somewhat obscure but worthy 

 worker, as for his own reward, and knowing that every nature- 

 loving student will be glad to learn that the longed-for end has 

 at last been secured, and that he can, without difficulty or expense, 

 avail himself of its accomplishment. It may also be here recorded 

 that it was the same industrious and deserving naturalist to 

 whom we are indebted for introducing the largely-adopted practice 

 of '' sugaring " for moths. — W. W., Highbury. 



[105] — Fungi axd Lichens. — In answer to "J. S.," in last Fri- 

 day's Knowledge, Mr. D. Bogue, publisher, 3, St. Martin's-place, 

 Trafalgar-square, publishes a book on British Fungi, by M. C. Cook, 

 M.A.. LL.D., which is, I believe, generally considered to be an 

 excellent work. 



[108] — The Eye as ont: op the Senses. — In answer to " T. T." 

 (query No. 128), the same publisher advertises a little book by Dr. 

 Dudgeon, entitled, " The Human Eye : its Optical Construction 

 popularly explained." Price 3s. 6d. — R. T. 



[IIOJ— The Coal Age and the Earth's Internal Heat. — The 

 fact that in the lower levels of the silver mines on the " Comstock " 

 lode in Nevada (say 1,600 feet from the croppings), the men can 

 only work fifteen-minute shifts, owing to the heat, may throw some 

 light on this subject. — E. F. B. Harston. 



[110] — The Coal Age and the Earth's Intern.il Heat. — The 

 theory that the earth was once in a state of fusion, has many sound 

 arguments in its favour, one being that the oblate-spheroidal 

 shape of the earth was produced by the exertion of the centrifugal 

 force on the molten mass of the earth, like a similar shape would be 

 produced if a mop were whii-led rapidly round in the hand. We 

 have the evidence of geysers and hot springs, and, to some extent, 

 of volcanos and earthquakes, that some of the original fire in the 

 earth's internal regions still exists. The increase of temperature 

 as we descend into the earth is 1° F., for every 50 or 60 ft. The 

 gigantic flora of the coal period was perhaps as dependent on the 

 internal as on the external heat which was exerted on it ; that is, 

 supposing, as most likely was the case, that the regions of fire 

 in the earth were, in those remote ages of time, much greater than 

 now, — each age "witnessing a decreased space of internal heat com- 

 pared with the preceding. — Herbert E. Weller. — [The answer 

 is rather crude, but some of the relations indicated are worth 

 studying. — Ed.] 



[131] — Creation. — Read also Lyell's "Antiquity of Man" and 

 Lubbock's " Pre-historic Times." — Paugul. 



[133]. — The Wesleyan Methodist Magazine for science article 

 every month. Good Words, of coming year, for articles on " Science 

 and Religion " ; also " Proceedings of the Royal Society," for a year 

 or so ago, contain — or will contain — articles by the Rev. W. H. 

 Dallinger. None of Mr. Dallingcr's lectures have been published, I 

 believe. — Paugul. 



[134] — Cheap Telescope. — Complete instructions to make a tele- 

 scope would, I fear, be too voluminous for this journal, requiring. 

 as it would, a page or two ; but if the querist will write to me I will 

 give him the information he wishes for. — Paugul. 



[136] — Sunlight on Fires. — It is useless to quote housemaids 

 about such things. It is absurd to suppose that sunlight prevents 

 a fire or a cigar from burning. The fire will appear to be out when 

 a bright light shines on it, and you let it go out when the sun 

 shines, because it is warmer then than at other times. The fire in 

 my study is in sunlight every day (if the sun appears), and sun- 

 light has never yet put it out. I can also testify that in India the 

 sun never puts out either fire or cigar. — Paugul. 



