Feb. 24, 1882.] 



KNOWLEDGE 



365 



(price los.) ; then, during the last year, ''Bcntley's Botany" (148.), 

 "Pereira: Materia Medica" (25s.), and " Fownes' Chemistry" 

 (188. 6d.). The least pcssible expense (exclusive of living: and 

 books) is £3s. 5s. ; the least time, three years — both expense and 

 time beinj^ generally very much exceeded. Capital required for 

 business, from ,£500 to iiJ.UUO. .\t present the game is not worth 

 the candle, but what the future of pharmacy in this country is, dolb 

 not yet appear. — Pharmacisi'. 



[233] — Biological. — John Hanipson will find the relative brain 

 capacity of the Neanderthal skull with man, with " illustrations," 

 also the geological formation in which it was found, in Lyell's 

 "Antiquity of Man." He will also sec, by reference to Dr. Morton, 

 Professor Uuxley, and others, what is, indeed, very easy of demon- 

 stration, that the difference between the brain powers of the higher 

 apes and the lowest savage is very much less than the difference 

 between the brain powers of the lowest savage and the cultivated 

 European. — F. Selby. 



[236] — The Polar Sun. — Neglecting the eUipticity of the earth, 

 it takes the same time as to decrease in polar distance by its dia- 

 meter (including + ) the effect of refraction, that is — 



90° -Href. =90° 34' 54" 



89° 27' 50" + ref.'-89° 5G' 33" 



38' 21" at -99" per min. =2,280 minutes, 

 and in 2,280' the sun's movement along the horizon + his own motion 

 (apparent, of conrse) ■= say 572°. — Tria. 



[236] — The Polar Su.n. — To an observer at the North Pole, the 

 rational horizon is coincident with the celestial equator ; the sun 

 will, therefore, rise above the jiolar horizon at the same instant as 

 he crosses the equinoctial at the vernal equinox. At this epoch 

 the change of declination (or angular distance from the equinoctial) 

 is at the rate of 59'27" per hour, and the apparent diameter of the 

 sun's disc at the same epoch is 32' 11"; hence the time occupied by 

 the rising of the sun's disc is found by division to be 3257 hours, 

 or 1,954 minutes, and the arc of the horizon moved over during 

 this time will be at the rate of 360 degrees per 24 hours, which is 

 488| degrees. A more rigorous method of arriving at the above 

 result (which is only approximate) is to calculate the exact instant 

 of Greenwich time when the sun's upper limb is on the horizon, 

 and then to repeat the calculation for the lower limb on the horizon. 

 The difference of the two times is the exact interval required. 

 Nothing, however, is to be gained by entering more minutely into 

 such purely technical calculations. The above result is probably 

 correct to a few seconds of time. — A. N. Somer.^cales. 



[247] — Warmth at Night. — Unless J. M. J. proposes to confine 

 himself entirely to the house, and unless he keeps his sitting-room 

 at the same temperature as his bedroom, a tire all night would cer- 

 tainly be injurious. The advice, however, that can be given in 

 this column will not be of much use to him. He should consult his 

 medical adviser, who can make himself conversant with every 

 symptom. Advice is best, as a matter of course, when it is based 

 tipon accurate knowledge. — Robert Macphekson. 



[248] — Lepidodendro.v. — To prevent the decay of fossil shells, 

 &c. : — Steep them in a weak solution of gum-arabic for several days. 

 All fossils taken from an exposed sea cliff of loose soil — as, for 

 instance, the drift shells of Blackpool — must be soaked in fresh 

 water for two months and then treated as above. The metallic 

 nodules you mention are concretions of iron-pvrites, the so-called 

 " Thunderbolts " of the Isle of Wight. No doubt the apparent 

 casts of vegetable remains are due to the crystallization of this sub- 

 stance. It is almost useless to carry home any fossils, however 

 fine, which contain a trace of this substance, for, though they may 

 be as hard as steel when first obtained, they will, sooner or later, 

 come to grief . If the "brick earth" of West Drayton be glacial 

 clay, the chances of finding any fossils are very remote. To 

 decide this question, look for ice marked boulders, such as that 

 figured and described in Knowledge, p. 345. Be particularly care- 

 ful to keep all fossils in a perfectly dry place ; I have seen many 

 valaable specimens completely spoiled by the neglect of this pre- 

 caution. — J. H. 



Goats to Protect Sheep. — The fanners of Hunterdon and 

 Somerset counties. New Jersey, use goats to protect their sheep 

 from dogs. Two goats can drive away a dozen dogs, and two are 

 about all each farmer puts in with his sheep. As soon as a dog 

 enters the field at night, the goats attack him, and their butting 

 propensities are too much for the canine, who soon finds himself 

 rolling over and over. A few repetitions of this treatment causes 

 the dog to quit the field, limping and yelling. Formerly, when a 

 dog entered a sheep-field at night, the sheep would run wildly around 

 and cr\' piteouslj-. Since the goats have been used to guard them, 

 they form in line behind the goats and seem to enjoy the fun. The 

 idea of utilising goats in this way came from the West, where they 

 are put in sheep-pens to drive away wolves. — A'. )'. Sun. 



an^n'6 to CoiTfsfponlicnts. 



*,* Ml eomrn'mtciifioiu for the Editor requiriug farty attention ehouUI reach the 

 Office on or Itefure the S^ilurdaii preceding the current i»ne of Ksowlkdqb, the 

 increating circittatioii ofKhich compel* us to go to preea early in the tceek. 



HiSTS TO CoBHEsPOSDmcTS.— 1. No quettiont atking for tdentiflc information 

 can be ansKrred through the poet. 3. Letters eent to the Editor for correspondents 

 cannot be fortcarded ; nor can the names or addresses tf correspondents he given in 

 aneieer to private inquiries. 3. No queries or replies savouring of the nature of 

 advertisements can be inserted. 4. Letters, queries, and replies are inserted, unless 

 contrary to Rule i, free of charge. 6. Correspondents should vrite on one side 

 onlv of the paper, and put drawings on a separate leu/. **• Each letter, query, or 

 reply should have a title, and in replying to letters or queries, reference should be 

 rtade to the number of letter or query, ihe page on tchich it appears, and its title. 



A. Arthur Reade. — I should be glad to give my experience of 

 the effects of smoking, but I smoke so little that 1 may practically 

 be said to have no experience in the matter. 1 never smoke unless 

 the presence of a great number of smokers renders it unpleasant 

 not to. As for alcohol, when 1 work hard, wliich is most of the 

 time, I find the less alc»hol I take the greater my working energies. 

 For eighteen months (some years ago) I took no alcohol, and 

 my work never went more easily. At present, even when 

 I work hardest, I do not go down to absolute abstinence ; 

 still, my working allowance is too small to make much dif- 

 ference one way or the other. — W. J. Collins. We quoted Dr. 

 Carpenter's address because of its intrinsic merits, not as 

 part of a discussion. For the discussion of a medical ques- 

 tion you should go to medical journals. — J. A. Miles. Many 

 thanks for the table ; but fear there is no space. The algebraist 

 can get any of the tabulated relations at once when he wants them, 

 others would not look at the table. Will try to find room for pro- 

 blems 1 and 2, as they are general. — J. (Ifkord. Many thanks. 

 There may be delay in appearance of your interesting communica- 

 tions ; but they will appear. The paper you wi-ite on quite suitable 

 for printers.— H. P. Cooper. Thanks; "willtry to find space for 

 new form of electrical accumulator. — G. E. Sutcliffe. Reference 

 to the key, after sufiicient attempts to solve problem, perhaps the 

 best course ; you should notice how the difficulties which had 

 foiled you are mastered. The best promise of proficiency in 

 your letter is your eWdent anxiety to become proficient. With 

 a little practice you -will probably succeed. — Wm. Datey wants 

 to know how he may soften animal hair without destroying 

 it or injuring its colour ; he would have been among the Queries 

 if he had put his question in proper query form. — T. J. P. Thanks ; 

 but why not follow rule and put title of query ? When we get 

 such a' reply as yours, we have to hunt up the query through 

 back numbers to get the proper heading, and our work is heavy 

 without this. It would be easy for you, with the iiuery before you, 

 to write its title. — J. McGrigor Allan. No space for articles or any 

 but very concise letters about mutilation of animals. Section V. 

 on other subject later if can find room. — S. S. S. S. wants best 

 book of Mechanical Philosophy for C.S. examination. Both the 

 French writers you name good popularisers of science, but without 

 mathematical kiaowlcdge, so that they are only to be trusted when 

 quoting the opinions of others. Lardner's " Museum " partlj' ob- 

 solete, but in part still tnistworthy. Impossible to answer more 

 definitely in space at our command. Magnetism cannot be inter- 

 rupted, as electricity, by non-conducting bodies. We use your 

 words, but they are inappropriate. — W. P. Wantage. Already 

 answered. — W. H. Sand. A. R. Molli.son. Answered. — Name- 

 LE.SS. 49, Victoria-road. Solution correct.— R. G., J. N. P., 

 A Le.arner, Phrensy, Eque.s, Ron. E. Ali.son, B. G. Morris, 

 and others. Dear sirs, how can we find time to work out such 

 sums as you send ? If we could hire a culculating boy, who 

 could tell "us in 2 gee. how long a wire -jVith of an inch in diameter 

 could be made out of a cubic foot of brass, or in 3 sec. how 

 often a cart-wheel 3 feet in diameter would turn if rolled a distance 

 equal to the sun's from the earth, &c., we would tell you all about these 

 things. One of you has taken an appropriate name. — Charles 

 Burns, noting that the Goat and Compasses = God encompasseth 

 us, desires to have corresjionding equations for the Pig and Whistle, 

 the Magpie and Stump, and the Bear and Ragged Staff.— Thos. Sid- 

 dall. Will insert queries if you will make them suitable. — B. M., 

 F.R.C.S. Thanks, suggestions noted. — A. M. Somerscales. 

 Thanks, will wait till C. T. B. explains what was really meant. Of 

 course, oblique is less than full illumination. In case of still 

 water, the brightness you mention is due to reflection, not to 

 surface illumination. But this was not C. T. B.'s difiiculty. — 

 A. J. P. Know of only one kind of aneroid, in which the box 

 is completely exhausted of air, the elasticity of covering 

 balancing the atmospheric pressure. — A. Ok.msby. Would give 

 vour problem (Napoleon's) for solution : but it is necessary to 

 reserve mathematical column for other matter. You will find 

 no difficulty in solving it if you go to work as follows : — Pay no 



