August II, 1881] 



NATURE 



335 



nished witVi an excellent index. It is an entertaining and 

 instructive book, and we wish it all success. 



George J. Romanes 



LETTERS TO THE EDITOR 



[The Editor does not Itold himself responsible for opinions expressed 

 by his con-cspondents. Neither can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. 



[ The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible otherwise to ensure the appearance even 

 of communications containing interesting and nczel facts.'\ 



Thought-Reading 



By the courtesy of Dr. G. M. Beard of New York I had the 

 opporlunity of witnessing some interesting experiments in arti- 

 ficial trance performed on one of his trained patients, thought- 

 reading being one of the phases exhibited. After his discovering 

 objects in the u;ual way, I used a fine copper «ire about a yard 

 in length. I wound one end round the right hand of the 

 patient (after he was hyperotised) and then placed his wired 

 hand against his forehead. The patient then wandered round 

 the room in an aimless sort of manner, the wire all the lime 

 being quite slack, but the moment I attempted, however gently, 

 to increase the tension just sufficient for him to feel it, he in- 

 stantly moved off along the direction of the w ire, like a horse with 

 a rein. I subsequently tried a thicker wire. The patient stood 

 with his face in a direction at right angles to my own ; he moved 

 straight towards the table on my left hand, and after oscillating 

 his head sideways as if trying to find some particular spot, he 

 finally brought his forehead slowly but with great accuracy down 

 upon a metal disk about lA inches in diameter, and at a distance 

 of about 18 inches from the edge of the table. This was exactly 

 what I had " willed." 



The different efiects produced by a slack and a stiff copper 

 wire respectively would seem to show, clearly, that the patient 

 cannot acquire the "will" of the operator unless the connection 

 be sufficiently rigid to communicate the involuntary muscular 

 action of the operator, however imperceptible sucli action may 

 be to the latter himself, who wills w hat the patient is to do. 



George Henslow 



A Gun-Signal Recorder 



In the judgment recently delivered by Mr. Mansfield on the 

 stranding of the steamer Britannic, he says : — " With respect to 

 the signals from the Hook Tower it is stated that the gunner 

 who discharged the gun — a twenty-four pound gun — commenced 

 firing at 1.50 a.m. on July 4, and continued firing at intervals of 

 ten minutes till 10.16 a.m. He took the time from his watch, 

 as his sandglasses were unserviceable ; he had no light but a 

 dark lantern in his gunhouse. Without imputing to him inten- 

 tional neglect of his duty or wilful misrepresentation, it seems to 

 the Court that he may have been less vigilant and less accurate 

 than men who were keenly awake to the difficulties of their 

 position, and who must have known that the safety of the ship 

 was involved in their taling the time between the signals with 

 scrupulous care. In his unsupported testimony the Court cannot 

 find that the signals from the Hook Tower were fired at regular 

 intervals of ten minutes. Looking at the importance of accu- 

 racy between the intervals of the fog-signals, the Court wish to 

 draw attention to the statement of the gunner that he has no 

 relief iu his duty, however prolonged it may be ; nor do the 

 Court find that there is any check, mechanical or otherwise, on 

 the gunner to insure accurate firing." 



The writer would suggest that a simple recording apparatus 

 might be made by means of a clock controlling the movement of 

 a strip of paper, as in the Morse telegraph ; this strip being 

 divided by transverse lines into spaces representing minutes and 

 seconds. 



A diaphragm of thin sheet iron, caoutchouc, or other suitable 

 material, connected with a metal point as in the phonograph, 

 would then register each exjilosion of the gun by depressing the 

 point on to the paper strip, and either making a pencil-mark or 

 a perforation. Such an instrument would be a check on the 

 accurate firing of the gun in the station where it was placed, and 

 the production of the strip would do much to remove the uncer- 

 tainty which appears to have existed in the case above cited. 



Liverpool, July 30 A. G. P. 



Symbolical Logic 



As Mr. Venn appears to be really serious in accusing me of 

 having misquoted him, I may as well give the whole sentence 

 which contains the statemeut which he says I distorted. The 

 complete sentence is this : — 



" Take, for instance, such problems as those of which Prof. 

 Jevons has discussed a sample under the name of Numerical 

 Logic (Pr. of Science, p. 169), as any of those which play so 

 large a part in Mr. Macfarlane's volume, or, still more, as tho^e 

 problems in Probaiihty which Boole justly regarded as the 

 crowning triumph of his system." 



I certainly thought that in this sentence the last relative pronoun 

 which referred to Boole's probability problems in general, but 

 especially to that much discussed problem (sometimes called his 

 "challenge problem ") which Boole gave in illustration of what 

 he conceived to be the superiority of his " general method " over 

 the usual methods. It never struck me therefore that Mr. Venn 

 would seriously accuse me of misquoting him because (in order 

 not to inflict upon the readers of Nature the irrelevant three- 

 quarters of the above sentence) I represented him as saying that 

 Boole "justly regarded his problems in frobaiility as the crown- 

 ing triumph of his system." What then are the problems to 

 which Mr. Venn refers? Thi.s, I own, Ls not a point upon which 

 I have "any claim to call for an answer," but I think it is a 

 point upon which he might courteously condescend to gratify the 

 natural curiosity of many admiring readers of his " Symbolic 

 Logic," who (unlike me, I am afraid) cannot be suspected of 

 any unkind wish to place him in a difficulty. 



Boulogne-sur-Mer, August 2 Hugh McColl 



Bisected Humble-Bees 



At the end of my garden two magnificent lime-trees grow on 

 which bees — of specimens of which I hereivilh send you por- 

 tions — feed at this time of the year by hundreds — by thou- 

 sands. What kind of bees are they ? But the following are the 

 points on which I should like seme information, livery morning 

 I find numbers of them on the ground, helpless, behaving very 

 much like men when they .ire drunk. What cau, es this? 

 Next, how comes it to pass that, apparently, these helpless hees 

 all become bisected or trisected as the specimens I send ? This 

 morning there are hundreds of portions under the trets. We 

 have a family of " fly-catchers " in the garden — would they do 

 1' ? T. Masheder 



The Grammar School, Ashby-de-la-Zoucb, July 29 



[The bees are a common species of Bombus (Humble-bees), 

 mostly workers, and mostly bisected at the junction of thorax 

 and abdomen. Perhaps wasps are the culprits, adopting this 

 method in order to rob the bees of their honey-bags. We'shall 

 be glad to have information on this point. — Ed.] 



A New Meter for Electric Currents 

 In Nature, vol. xxiv. pp. 294-5, you notice a new meter for 

 electric currents, giving a description which is fairly correct for a 

 slight sketch, and attributing the invention to Mr. Edi-on. The 

 invention, however, is not American, but English, and as the 

 inventor, 1 think myself entitled to whatever credit this entirely 

 novel system may merit. My patent rights for America have 

 been purchased of me, and the invention will be shortly in use 

 in New York. John T. Sprague' 



Birmingham 



[Our correspondent is doubtless right in his claim. Never- 

 theless the invention we referred to in the brief note in ques- 

 tion has been recently patented in this country on behalf of 

 Mr. Edison, presumably at a later date than our correspondent's 

 invention. We should be glad if he would kindly furnish us 

 with the date of his English patent. We certainly meant no 

 injustice in publishing the note. — Ed.] 



A POPULAR ACCOUNT OF CHAMELEONS'' 



II. 

 'T*HE next most interesting of the animal's lifeprocesses 



•^ is its change of colour. Mistakes and exaggerations 

 as to this matter are of very old date. Aristotle believed 



^ Lecture delivered at the Zoological Gardens on lulv 2S tR.9t k,. c» 

 George Mivart, F.R.S. Continued from p. 312. ^ . "i>i, oy st. 



