Feb. lo, 1887] 



NA TURE 



545 



must employ a, fl, y, as defined in Mr. Watson's letter in your issue 

 of January 27 (p. 296). These mechanical forces cannot, I believe, 

 be expressed in terms of the values of a, k, <-, «, v, w, and their 

 differential coefiRcients at the point. This is a definite physical 

 argument in favour of the existence of o, /3, y, within a magnet. 

 St. .Moritz, Engadine Jamks C. McCoNNtL 



"Phantasms of the Living" 

 NoTHiNT. in your last week's notice of " Phantasms of the 

 Living " gratified me more than the attention paid to our experi- 

 mental results. The grounds of our own confidence in them are 

 (i) that the conditions were in many cases such .as completely 

 to exclude unconscious physical signs, and (2) that, if the success 

 was due lo fraud, it was not fraud which the investigators failed 

 to detect, but fraud in which they must actively have shared. 

 Hut, where the scientific presumption against new phenomena is 

 so strong, it is best to recognise that no line can be drawn at 

 which the evidence for them might to be found convincing, and 

 that, till it actually is found convincing, it is incomplete. Mean- 

 while it ought to be sceptically approached — not with the 

 impatient scepticism which denies that such facts can ever be 

 ])roved, hut with the cautious scepticism which perceives that 

 they reipiire a very great deal of proving. The object of this 

 letter, then, is to urge the paramount importance of rxleuding 

 the area of experiment. This cannot be done without an amount 

 of public spirit which it is very hard t) evoke. The " percipient " 

 faculty, even though possessed in a high degree, is very unlikely 

 to reveal itself spontaneously : our only hope of discovering it 

 is that tri.als in thought transference shall be very widely made — 

 which means that a large number of persons shall spend some 

 time and trouble in a manner which will often appear to have 

 been fruitless. It is diHicult to press this on anyone as a duty ; 

 but it is at any rate worth while to point out how simple and 

 rapid the process of experimentation may be made. Especially 

 anxious am I that a great many pairs of persons should carry out 

 experiments of the very simple type described in " Phantasms," 

 vol. i. jip. 32, 33. If any of your readers are willing to do this, 

 will they kindly, before beginning, send me their names and the 

 number of the trials that they propose to make, to guard against 

 any ^/i-f/j'f;/ of results ? Edmund Guknev 



14 Dean's Yard, S.W., February 3 



University College, Bristol 



My atlenlion has been called to a paragraph in your issue of 

 the 3rd inst. (p. 326), referring to this College. Will you kindly 

 grant me space to correct the statement made therein, which is 

 inaccurate in soaie important points, and is calculate 1, as it 

 stands, to injure our reputation ? 



No general reduction of the salaries of the Professors has 

 been made, nor is it contemplated. Notice to terminate our 

 engagement with two Professors h.as been given them, .as it was 

 l>elieved that more advantageous arrangements could be made in 

 their departments without affecting the quality of the instruction 

 given. It is too true that the College greatly needs more liberal 

 pecuniary support than it has hitherto received, but efforts are 

 iieing made to jirocure it ; and .as yet the CouDcil have no inten- 

 tion of limiting the su*>jects hitherto taught, or of requirin';{ a 

 lower standard of attainment than that which has distinguished 

 so many of their Professors. Albert Fry, 



Chairman of the Council 



University College, Bris'ol, February 7 



A Rule for escaping a Danger 



Si;i'POSE a weir, AR, across a river, and first let it be al riLjht 



angles to the direction of the current. Suppose a man in the 



stream above the weir, nearer to B than to A. Let U he his 



position, and OX a perpendicular on AB. Then he cannot 



BX 



escape if his velocity, v, is < . «, where u is that of the 



OB 

 stream. If bis full speed has this critical value, or if there is 

 any uncertainty about his safety, he must swim at right angles 

 to 015. 



The nde is obviously correct, for to escape he must clear the 

 nearer end of the weir, and must therefore exert his strength in 

 the direction mentioned. Geometry puts it clearly : Kc<luce the 

 s Iream to rest so that the weir is advancing on the man with 



velocity 11. Let P be the point at which the 1 

 then, if PN be perpendicular to AB, 



OP PN 



so that P is on a conic for any given velocity. Varying v, he 

 will escape if the conic reaches the bank. The first to do so 

 touches at the end C of the minor axis, and since CB is a 

 tangent, the angle COB is right. Also now 



2':k = OC:CB = BX : OB. 



If the weir slants across the river, the direction of safety is 

 still at right angles to the line joining O to A or B. The 

 swimmer must decide, by looking in both directions, to which 

 bank to direct his efforts. The locus of points for which both 

 directions give the same distance is, to axes through the middle 

 of the weir up and at right angles to the current, of the form 



{,}".x - 2aby + b''x)(y''-a - ibxy -f ab') = by{x- — a'-f, 

 a quintic having cusps at A, B. 



The rule fails if the change of velocity as one approaches the 

 bank be considerable. One would then strike more across. 



If one were being charged by any insensate object, the rule 

 would of course apply. Frank Morley 



Bath College 



Abnormal Cats' Paws 



In reference to the recent articles in Nature on six-toed 

 cats, allow me to remark that the experiment about to be tried 

 on one of the small islands off the English coast has apparently 

 been anticipated at the village of Morriches Centre, on Long 

 Island, where nearly all the cats have at least one supernumerary 

 digit on all feet, and are currently called, in the jdace, " double- 

 footed." I have a specimen showing the abnormality distinctly. 

 I say "apparently," because there can be little doubt that at 

 some time a single individual was introduced, which has become 

 the ancestor of all the "six-toed" cats in the village. 



E. W. Claytole 



Abnormities in cat-s' paws occur rather frequently in Massa- 

 chusetts. They are called mitten cats, and are much in demand 

 because they are considered to be good mousers The first I 

 ever saw was a male yellow tiger, whose four paws had two 

 extra toes sirongly developed. A little stray fe nale kitten which 

 was brought up at my house had two abnormal fore-paws with 

 four extra toes on each. As there are no mUe cats in our neigh- 

 bourhood with any abnormity I was very anxious to sea whether 

 her young ones would inherit the shape of their paws from the 

 father or mother cat, and whether some abnormity would also 

 appear in the hind-paws. She had eight, and only one of them 

 with four normal piws ; all the others inherited from the mother 

 the abnormal fore-paws, some even h<iving five to seven extra 

 toes, with perfectly developed claws and pads. I did not pay 

 attention to the sex, but brought one up on account of its strong 

 build, which turned out to be a male, and another for its beautiful 

 stripes, which was a female. The old cat rested nearly a year, 

 and then again had eight three time", in succe sion, in April, 

 June, and October, and every time only one with normal paws. 

 Tile mother is a pale grey tiger, and each one of the young ones 

 was differently spotted, and, as I believe, had a different father, 

 as I recognised the marked resemblance to the various visitors to 

 our garden I paid no attention to the sex, but brought up fron 

 the last litter the strongest looking, which turned out to be a 

 male, and two others — the one selected by a chil I, the other 

 because it had seven extra toes. Both these were females. 



H, A. Hagen 



Harvard University, Cambridge, Massachusetts, January S 



The Cross as a Sun Symbol 

 The use of the cross as a sacred symbol dates from the earliest 

 times, and is almost universal. It occurs upon the monuments 

 .and utensils of every primitive people from China to Yucatan. 

 In many, perhaps in a majority of, instances it i- used as a 

 symbol of the sun. One of the oldest and most widely occur- 

 ring forms is the cross with cnmpons turned to the right o- lefi, 

 the svaslika and saiO'a>tika of India, the " Thor's hammer" of 

 Western Europe. Prol. .Max MiiUer thinks that the si'aslika 

 represents the vernal -sun, and is hence an emblem of life, 



