March 31, 1882.] 



KNOWLEDGE 



479 



Would you bo kind enough to give an explanation of this appaient 



:ira(!iix ? If this is not one, is it ever true that the conditions of 



: 11 man thought involve contradictions where it transcends the finite? 



of course, Kant says that our ideas of space and time are forms of 



thought founded on no realities. But apart from this hypothesis, can 



:i logical explanation of such problems as the above be supplied ? 



!'i rliaps this might be combined mth the suggestion of J. S. T., in 



lor 295, if, as I and many others hope, you are going to give an 



I'icle on space. Eton. 



This paradox resembles Aristotle's proof of the finiteness of 



U.0, which never satisfied any one (as Sir J. Herschel remarks), 



ugh unanswerable, — viz., Since whenever we take any two points in 



■ universe, the straight line joining them is finite, the universe itself 



iinite. But as this depends on the first postulate of Euclid, so the 



:i-^wer depends on the second; — Each of Aristotle's finite straight 



tiis can be produced to any distance in the same straight lino; 



reforo the universe is not finite. Lastly comes the third postu- 



■■. which since it asks us to admit that a circle can be drawn 



\ ing anj- centre and at any distance from that centre, coiTosponds 



li Pascal's saying, that the centre of the universe is every\vhere, 



s circumference iiowhere. — Ed.] 



AN IDIOT DOG.— AN EXCEPTION PROVING A IJULE. 



o&l] — I once possessed a black cmly-haired Xe^vfoundland and 



rricver, weighing 125 lb., and standing 2 ft. 4 in. high, as you 



uld measure a horse. Despite his beauty and magnitude, he 



::s, however, it not an idiot, certainly the least intelligent dog I 



1 rsaw. Asa yard dog he was quite worthless, except that his 



.liiuizing size terrified alike the honest and dishonest — i.e., in day- 



liglit, for let come what or who would, he opened not his mouth. 



Ill the house ho was equally crass. In his movements ho seemed 



to have but one idea, and if a table or a child were in his way, 



down they would go — Lion cared not. If taken out of doors he 



would go straight ahead, neither kno\Wng his master nor his way 



home, his solo and great delight being to slay any dog approaching 



him in size. 



. I have recently read a translation of a work on " Mind in 

 Animals," by Lnd^vig Buchner. Although he only describes ants, 

 bees, wasps, and spiders, yet he succeeds in annihilating the old 

 " instinct " superstition. Students of the subject of mind in 

 animals should read this book. Joseph Wood. 



WOOD-GAS. 

 [365] — I repeat that carbonic anhydride can bo perceiTed by the 

 organ of taste and by the organ of smell. If " F. C. S." considers 

 that the taste and odour are due to impurity in the COo, as is the 

 case with hydrogen, will he state what this impurity is ? The 

 flame of CO was observable as I wrote, over a red-hot fiie without 

 flame, which I call a "sluggish fire." The process of CO from COn 

 and heated carbon is nothing new ; it is to be found in many text- 

 books. The main point, after all, in the use of such gas, would be 

 the danger of an escape. Lewis Abuxdel. 



NOTES ON ROWING. 



[366] — "Notes on Rowing" are very acceptable, and, happily, 

 promise more. Rowing, too, is not the only instance of propulsion 

 by pressure upon a lever of the second order. The tractive force 

 of a locomotive engine can be explained in the same way. To draw 

 a parallel, one might say that the rail corresponds to the water, for 

 it is the fulcrum. The axle-boxes are the rowlocks ; the crank-pin 

 is the " spool " of the oar, and the peripherj* of the driving-wheel is 

 the " blade." Each end of the cylinder (which, by the way, sits 

 like a rower, forward of its work) is in turn a " footboard " against 

 which the steam reacts with a force approximately equal to the 

 pull or thrust upon the crank-pin. And, to make the parallel com- 

 plete, I may say that the " slip " of a driving-wheel when an engine is 

 Pmming at high speed is at the present time the subject of experi- 

 ments. Of course, the action of a driving-wheel when the crank is 

 below the axle has no parallel in rowing, but it is a good exercise for 

 the student of mechanics to prove that the foovard pressure upon 

 the engine is the same on each stroke, in spite of the difference in 

 leverage. Lastly, the motion of the piston of the engine corresponds 

 pretty accurately with the motion of a rower's body— back^vard and 

 forward with respoct to the boat, but continuouslj' forward (although 

 with a varying velocity) with respect to the water. Take any point 

 in the periphery of the driving-wheel, too, and see how it goes from 

 a condition of rest when in contact with the rail to acquire a 

 velocity equal to double the velocity of the train when at its highest 

 point. 



In the same way, the oar blade, from being nearly stationary in 

 the water, suddenlj- leaps forward with a velocity (that is, if 

 nothing happens) at least double the boat's speed. Is the parallel 

 complete ? — Yours, &c., A. N. S. 



ELECTRIC TELEGRAPH. 



[367] — Ronald's electric telegraph (see Knowledge, XIX., p. 

 401), is by no means the oldest known piece of telegraph aparatns. 

 Professor Siimmering (1 am not quite sure of the spelling of the 

 name), of Munich, constructed, in 1809, an elcdric telegraph, vthich 

 is preserved in one of Munich's numerous museums, and was 

 originally laid down between Professor S.'s laboratory and that of 

 one of his learned colleagues. A description and drawing of it are 

 given in " Das Buch dor Erlindungen," publ. Otto, Spamer, Leipzig. 

 1 give an extract in the following : — 



There were as many circuits as the alphabet has letters, further 

 figures, signs, i'c., between the two stations. Each of the circuits 

 was an apparatus for decomposition of acidulated water, by means of 

 the galvanic current. The tubes containing the water represented 

 letters, &c. The rising of gas bubbles in a certain tube indicated to 

 the receiver a certain letter. There was only one battery, which 

 could bo connected to all circuits by means of switches. There was 

 also a cleverly-designed signalling apparatus to attract the receiver's 

 attention. One tube contained a glass bell, under which the poles 

 were situated, gas evolution would drive out the water of the over- 

 turned bell, and cause it to rise, move a lever, and set a clockwork 

 going. This is written after a lapse of Tear.=! since I read the 

 description, and there may be some slight incorrectness in the 

 details, but I have given the general idea correctly. — Yours, &c., 

 F. Stern, D.Ph. 



VEGETARLiNISM. 



[368] — I wish to make a few remarks on the letter 207, p. 251, 

 in which the writer politely calls vegetarians " amiable fanatics," 

 and further adds that they seem determined to force their way into 

 the columns of Knowledge. This is a very grave charge indeed. 

 Will the writer kindly state the number and date of Carjjer's 

 Quarterly Journal, in which Dr. Wald's statement about the 

 prisoners in a castle at Waltenburg is to be found ; for in the 

 interests of truth and humanity this case requires careful investiga- 

 tion. For example, it would be important to know whether the 

 bread given to the prisoners was white, and if much salt was taken 

 with the leguminous food mentioned. 



It might bo also useful to know the proportions of meat to 

 vegetable diet partaken of, as a rule, by the writer of letter 207. 



So far as my knowledge extends, I find that the greatest intellects 

 of the present and the past have been either altogether or almost 

 akreophagous. 



As I write for the sake of information and not of controversy, I 

 am thankful that the columns of such an excellent paper as 

 Knowledge are open to the discussion of this important question — 

 viz.. What is the best food for the million ? 



Why should abstainers from flesh, fish, and fowl be honoured 

 with so many conflicting titles ? In the few numbers of Knowledge, 

 in which the subject of vegetarianism has been mooted, I find them 

 described as "phytophagists," devourers of "potatoes and turnip- 

 tops," " eaters of greens," &e. C. L. Poechek. 



TELEPHONE. 



[369] — I have been much interested in " G. E. V.'s " description 

 of the telephone, and should like very much if he would follow it up 

 by an account of the microphone transmitter. In making the 

 telephone, '* G. E. V." does not say how much wire he puts on his 

 bobbins, nor the number of it. Would he oblige by stating what 

 length and number he considers most suitable ? W. B. 



Notes on Science. — The former pupils of University College 

 School have raised a fund for the encouragement of science amongst 

 the boys at their old school. Besides an CNhibition for practical 

 chemistrj- and a prize for experimental jjliysics, thej- have founded 

 a medal, which wiU be awarded, at most annually, for original 

 work of sufficient merit in any branch of experimental science done 

 within a stated period of leaving the school. The medal, for the 

 design of which the contributors are indebted to Mr. Thomas 

 Woolner, R.A., will be exhibited in the Royal Academy this year, 

 and a copy ^vill be deposited subsequently in the British Museum. 

 It is not for us to criticise the work of that distinguished sculptor ; 

 those who have seen the copy belonging to Mr. Temple Orme, 

 pronounce it to be one of the finest medals ever struck. 



