122 



KNOWLEDGE 



[hvic. 0, 1881. 



lu the tludtnt wants cnnalwnyKlio ndilcd, and the clionp instnimcnt 

 mnde as complete on tho most expensive. It ie a great iiiifltake for 

 a bOLTtiiier to liave loo lnrf;o and complex an ini>trument, and the 

 iliffercnce in view through a very large glass coni)iared with an 

 onlinary one, such as is here referred to, is not so great as would be 

 imagined. 1 may add, that the eye can bo educated the same as 

 the hand, and, after a time, "Twenty" will be able to see mnch 

 more tliroufrh his glass than when ho storted. A novice looking at 

 .lupiter, for instance, will see but a small blank disc, but a practised 

 observer, looking through the sunio telescope, will sec a multitude 

 of interesting details on the planet's .surface quite invisible to tho 

 former. It is scarcely necessarj- to add to the foregoing that for 

 £."> a very good second hand instrument can sonictimes bo got by 

 ailvertising. There is no occasion, either, to reply to " Twenty's" 

 other telescopic qneriea, as I see the Editor promises an article npon 

 the subject. Albkkt P. Holden. 



107, Hoxton-etreet, N. 



COMETS' TAILS.— RAINFALL AND FORESTS.— THE OLFAC. 

 TORY TRACT.— INTELLIGENCE IN ANIMALS. 



[1 10] — 1. There is a question I should like to ask you with re.spect 

 to comets' tails, viz. ; Has the spectrum of the tail ever been 

 obtained ; if there has been one taken, was there any alteration or 

 new band observed in the spectra ? I look forward eagerly to the 

 continuation of your articles on the stxbjcct, for, I am sorry to say, 

 I am very ignorant on the subject. 



2. With respect to your article on the Fiji Islands, I noticed the 

 interesting circumstance of the rainfall diminishing simultaneously 

 to the cutting down of timber. Was it not the same with the Island 

 of Ascension, onlv in a still more remarkable degree ; for had not 

 the inhabitants to plant trees again, so that they might be a^in 

 blessed with rain ? I should be glad if you would inform me if I 

 am correct in the above, for I do not know where to look to refresh 

 my memory on the subject. 



3. In reading " M. L.'s" article on " Vivisection," an idea occurred 

 to me connected with the olfactory tract, on which I should like your 

 opinion. It is this : — A good many years ago my cousin and self were 

 working in the same " Lab.," and by accident he smashed a full 

 Winchester of N 11,110, with the natural result that he was half- 

 snffocated ; but the part I am curious about is, tliat from that daj- 

 to this he has had neither taste nor smell. Do yon think that the 

 dose of NHj destroyed that part of the brain referred to by 

 W. L. ? 



4. "Intelligence of Animals" : — I am in a position to give 

 rather a curious case of the intelligence of rats, proving — as does 

 your article — the practical, but if wo look at it in rather a favour- 

 able light, might prove even the abstract, which is wanting. 



The rats in this case also " bored " through a lead pipe ; so far 

 there is no difference to the example in your p.aper, and you will think 

 this is one of the " two and two equal four letters " ; but this lead 

 pipe, unfortunately for my father, was in the *' hold " of one of his 

 ships, and through their (the rats) craving for fresh water, and 

 getting it, a great <leal of damage was done ; they actually did hit 

 on the fi'esh uater lead pipes in preference (may I say) to the other 

 salt water ones (leading from the W.C.'s on deck, I mean, which, as 

 you arc aware, are cleaned by salt water.) This, I think, is a curious 

 coincidence, for might it not be turned by scientists either 

 way, either to accident or to sagacity on the part of the rats ? — 

 Yotirs, Ac, F. C. S. 



MEN'S HEADS. 



[ 120] — I have read carefully the letters on the size of human 

 heads. I am inclined to think that our heads, as a nation, are 

 smaller. The size of the head corresponds to that of tho body, so 

 that large heads mean large bodies. This is seen amongst navvies, 

 agricultural labonrers, and Irishmen from country places. Now-a- 

 days machines do a great deal of our mechanical work, and our 

 muscles getting less exercise, are not so large, .\gain, living in 

 towns, and having little bodily exercise or hard work, means small 

 bones and smaller frames altogether. The size of the head 

 increases with that of the body, so exercise ought to bo part of the 

 system at our public schools, and then we get a sound brain in a 

 healthy body. T. R. Allinsox, L.R.C.P., Ac. 



[Ou'inj to the extraordinary pressure of correspondence, our article 

 on " Comets" (illustrated uilh views o/ the destroyed comet of Biela) 

 is deferred till next u'eek. Wc must earnestly entreat our corre- 

 spondents to he concise, and only to write when they have somelhing 

 really interesting and new to communicate.^ 



©ufnesf. 



[C7] — Rainbow. — I should very much like to know why it in that 

 a rainbow is semicircular!' — G. 8. JI. 



[68]— Solar Storms. — By what method is tho velocity of wind. 

 Ac, in the sun ascertained ? — G. S. M. 



[09] — The Moon'.s iNfLCENCE. — It has been stated by Dr. Ball 

 that the result of the moon's action on the tides is to drive the 

 moon further and further away, and that the consequence of this 

 is that the day is getting longer and longer. He says that 

 50,000,000 years ago the mofm must have been very close to the 

 earth, at which time the day would be only three hours long. 

 Will yon kindly say if what Dr. Ball says is correct 'f and how the 

 action of the tides drives the moon further and further away, and 

 how the distance of the moon regulates the length of the day? — 

 E. K. [Will shortly make the question the subject of an article. 

 Dr. Ball's general conclusions are sound ; the detailed results he 

 would not, of course, regard as exact. — Ed.] 



[70] — Seismometer. — A description of an approved form of 

 seismometer would be much valued by M. A. F. 



[71] — Names ok Fi/iwers. — Can you let me know, by means of 

 your valuable paper, ofjany botany which will give the Latin and 

 English names to all flowers, 4c., and thereby mnch oblige. — R. D. j 



[72] — Antiquity of the Pvramids. — " Sir John Lnbbock, .speak- 

 ing of the antiquity of man, in his address at the late meeting of 

 the British Association, said that ' The researches in Egypt seem to 

 have satisfactorily established the fact that the pj-ramids them- 

 selves are at least 6,000 years old,' and mentions Professor Raw- 

 linson's researches in support of this." What is the evidence on 

 which this alleged antiquity is based ? — Actinolite. 



[73] — Clouds. — Is there any explanation of the peculiar forms of 

 Cirri and other clouds, esiiecially that known as a mackerel sky ? 

 If a large, flat vessel of water containing a little sediment is agitated 

 slightly, the sediment is deposited on the bottom in forms resem- 

 bling those of some clouds. Are the latter supposed to be formed 

 in a similar way ? — E. C. R. 



[74] — Experiment on Solar Heat. — I have read somewhere that 

 if one side be removed from a box (the interior of which is blackened), 

 and in its place tliree panes of glass w-ith spaces between them con- 

 taining air are inserted, water placed in a vessel in it may be raised 

 to boiling-point by the exposure of the box in its modified form to 

 strong sunshine. How is it that the heat, when in company with 

 the sun's light, can penetrate the successive layers of glass and air, 

 yet when deprived of its Inminoas companion, is retained in the 

 heat-trap ?— E. C. R. 



[75] — The Radiometer. — Would it be asking too mnch of onr 

 Editor to request that a series of papers explaining and describing 

 the little that is known as yet of the forces and phenomena con- 

 nected with the high vacua and radiometers might be given before 

 long in the very interesting pages of Knowledge ? — E. C. R- 



[76] — Planetary Movements. — The earth moves round the snn 

 because of the latter's attraction, i.e.. but for the sun's attraction, 

 the earth would move forward in a straight line. The attractive 

 force of the sun must, therefore, necessarily retanl the forward 

 motion of the earth. Is not this so ? If yes, does the earth s.'o 

 more and more slowly round the sun, and will it not ultimately stop 

 and be drawn into the sun, and when ? If no, what is the force 

 which causes the earth not to go more and more slowly'" — E. F. B. 

 Hab.^ton. [The answer to first question is " no" ; and that, there- 

 fore, no force is required to prevent the earth from being retarded. 

 Why should a force at right angles to her course retard tho e.-u'th f 

 Her path not being absolutely circular, the force of the sun some- 

 times slightly hastens and at others as slightly retards the e.arth -. 

 but in the whole year changes not her speed at all. — Ed.] 



[77] —Terrible Dreams. — What explanation can be given of the 

 horrible dreams that sometimes occur to persons ? — S. S. S. S. 



[78]— Antip.\thy and Sympathy. — What is the explanation of 

 the extraordinary antipathy felt by some persons against some tame 

 animals and things ; and the converse— extreme sympathy, almost 

 amounting to infatuation, shown by other persons (innate, not 

 acquired) ? — S. S. S. S. 



[79] — Mental Physiology. — Whose works are now the best 

 authorities on the study of mental physiology ? — S. S. S. S. 



[80] — The Cuin. — It has been said that man is the only animal 

 having a chin. Long before recent attention was called to the de- 

 ficiency of this feature in a certain homicidal criminal, observation 

 had led me to note various ca.ses of cruelty perpetrated by almost 

 chinlcss people; once, indeed, by a very young creature of twelve 

 years old, described truly, I think, as " a perfect brute." Where 



