October 28. 1S9;] 



NATURE 



613 



LETTERS TO THE EDITOR. 



The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents Neither can he undertake 

 to let urn, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of NATURE. 

 Xo notice is taken of anonymous communications.'\ 



On the Meaning of Symbols in Applied Algebra. 



Referring as briefly as possible to Prof. McAuIay's letter 

 on page 588, I contend (i) that no comjilex reasoning is neces- 

 sary to show that the commutative and associative laws hold for 

 the symbols of units or (better term) standaids ; a simple method 

 was indicated in vol. xxxviii. p. 281 ; and (2) that meaningless 

 things like the square root of a foot do not appear in any correct 

 final result. It is true that the square of an hour is meaningless 

 too, but the apparent occurrence of such a thinq;, in acceleration 

 for instance, is otherwise explicable ; for velocity is a real and 

 simple physical quantity. 



Magnetic intensity is not really the time rate of the square 

 root of a linear density, as Prof. McAulay imagines that physi- 

 cists suppose it to be ; he has omitted an essential factor ; and 

 when we discover the real nature of ;u, we shall find it 

 such as to satisfactorily rationalise the gibberish he properly 

 "abhors." If, for instance, ju turns out to be an etherial 

 density, the specification of H would be length divided by time. 



University College, Liverpool, Oliver J. Lodge. 



October 22. 



Strange Instinct of Fear in the Orang. 



The following circumstance which occurred at the Zoo on 

 Sunday last, and was witnessed by Mr. W. E. de Winton and 

 myself, is perhaps worth putting on record. 



We were watching and making friends with the baby orang, 

 and my wife was standing by, holding on her hand a muff manu- 

 factured out of the skin of the Indian flying-squirrel, with the 

 unstutfed skin of the head to the front, and the bushy tail 

 hanging loosely over it. Suddenly, but quite gently, she 

 stretched out the muff towards the orang, but at the sight of 

 the advancing fur a light of unmistakable terror sprang into the 

 creature's eyes. Upon repeating the experiment, the ape 

 promptly rolled over liackwardsas the quickest way of removing 

 himself from the immediate vicinity of the terrifying object ; 

 then gathering himself together, climbed up the branches of his 

 tree, and retreated to the back of (he cage, keeping all the 

 while a wary and frightened eye upon the muff, as if in fear of 

 an attack from behind. It is interesting that the whole per- 

 formance was carried through without the utterance of a sound 

 on the part of the orang ; but that he was acting under the in- 

 fluence of fear, there is, I am persuaded, no doubt. His 

 behaviour, in fact, reminded me irresistibly of the behaviour of 

 a friend's little child of ten months old, who evinced similar 

 signs of fright upon being shown a toy fur monkey for the 

 first time. R. I. PococK. 



Natural History Museum, October 25. 



Hence we have two broad results : ( i ) the excessive preponder- 

 ance of fillies over colts ; and (2) that the colts more frequently 

 resemble the colour of the dam than do the fillies. For every 

 hundred fillies there would be 102 colts resembling the dam. 



Truly this is not a large difference, but, based as it is upon over 

 1500 cases accurately described and exactly tabulated, it seei^s 

 worth calling attention to, as it carries Mr. Galton's analysis a 

 step further, and points to the possibility of a further develop- 

 ment in an exceedingly interesting branch of heredity. 



Churchfield, Edgbaston. * F. Howard Collins. 



Hereditary Colour in Horses. 



Mr. Franxis Gai/ion's very characteristic article in the 



current number of Nature, p.ige 598, upon hereditary colour | 



in horses, appealed to me with more than usual interest, as for ' 



some months I have been planning a somewhat extensive inves- \ 



ligation into theheredilary transmission of various characteristics i 



amongst the higher members of the animal kingdom, including 1 



that of colour in horses. j 



It may be of interest to your readers if I summarise a recent j 



<|uite preliminary investigation upon the same matter, which I I 



shall hope at some future time to work out more thoroughly. I j 



may add that, contrary to what Mr. Galton experienced with | 



the data he used, all the grey foals in my data did not come from | 



grey dams. | 



An examination of the offspring, numbering in all 1566, of ; 



(jne special class of mares shows that there were 686 offspring ; 



which resembled the general colour of the dam, and 880 which | 



differec] ; or a preponderance of 28 per cent, dissimilar. Of I 



these : — I 



313 colls were the same in general colour as the dam. j 



394 M M not „ „ ,, ,, ,, I 



373 fillies ,, the same ,, ,, ,, ,. 



486 ,, ,, not ,, ,, ,, ,, ,, 



Dog Running on Two Lejs. 



It is not necessary that a dog should be compelled by accident 

 to resort to this mode of progression (p. 588). Some years ago 

 I had a clever little Scotch terrier which would occasionally run 

 in this way. It would balance itself on two legs, sometimes on 

 one side and sometimes on the other, holding the other pair up, 

 and run with perfect ease for a considerable distance. As this is 

 the only instance I ever met with, or heard of, I do not suppose 

 that the accomplishment is a common one with dogs. 



Highfield, Gainsborough. F. M. BURTON. 



T//E OBSERVATION OF METEORS, WITH 

 ESPECIAL REFERENCE TO THE LEONIDS. 



TOURING the next few years a large amount of attention 

 -*-^ will be given to meteoric astronomy in general and 

 to the great shower of Leonids in particular. The pre- 

 sent may, therefore, be an appropriate time to refer to a 

 few points connected with this interesting branch. It 

 has often occurred to the writer that it would greatly 

 facilitate the comparison of different materials if observers 

 adopted one uniform method of recording meteor-flights. 

 Some merely give estimated compass bearings, and a 

 rough guess at the altitude and inclination of path, others 

 give the place and direction according to conspicuous 

 stars near, others simply mark the courses on a map 

 without reading off the individual positions, while others 

 give the R.A. and Decl. of both beginning and ending of 

 every object observed. It would be a great advantage 

 if every one tabulated results according to the latter 

 method. It can easily be done if the tracks, as observed, 

 are pencilled upon a celestial globe or star chart, and the 

 positions read off ; and this is a much more exact method 

 than describing the flights by stars near which they 

 happen to pass. 



Another point is that the accurate observation of 

 meteors demands a considerable amount of practice. It 

 would, therefore, be a most useful preparation for in- 

 tending observers of the Leonids if they carefully 

 watched the Perseids of August, Orionids of October, 

 and some other prominent displays, and gained a little 

 practical experience of the work. They would find it of 

 material assistance to them, and would enable the 

 Leonids to be observed more expeditiously and correctly 

 than must otherwise be the case. Accounts are some- 

 times published of meteoric showers by persons who are 

 reporting a perfectly novel experience, and it is not too 

 much to say that such descriptions are useless as regards 

 many essential details. A perfect novice may of course 

 stand and count the number of meteors visible, and may 

 be capable of describing a star-shower in a general 

 way, but he is heavily handicapped when it comes to 

 recording the more difficult features with precision. 



What photography may achieve in meteoric work we can- 

 not definitely foresee, but it is quite certain that the proper 

 observation of meteors, as at present conducted, demands 

 the work of a lifetime. A man must watch for meteors 

 all night, and suitably record them, and by day he must 

 analyse the observations and determine the radiant 

 points. The observer need not, perhaps, absolutely 

 isolate himself from all other work ; but the meteoric 



NO. 1 46 1, VOL. 56] 



