260 



♦ KNOWLEDGE ♦ 



[Oct. 26, 1883. 



also points out an easy method of carrying out such a 

 project. 



The addition of the finest examples from the southern 

 shores of Europe and from the coasts of America might 

 easily have rendered this display at the Fisheries not only 

 the largest, but, at the same time, the most varied and 

 complete that had hitherto been witnessed. At present, 

 no foreign specimens are exhibited, and it is to be feared a 

 great opportunity has been lost of making the anemone 

 exhibition, as it surely might have been made, a world- 

 wide emporium for the reception and comparison of the 

 finest known specimens. 



Dr. Ball's experiment, made apparently with a view of 

 demonstrating the peculiar jireference of this species for the 

 society of the hermit crab, has been humorously narrated 

 by Dr. Wright, of Dublin, and briefly is somewhat as 

 follows : — One of the specimens attached to the shell of a 

 Buccinum uiidaium, which it was inferred had only just 

 been deserted by a Pagariis, was placed in a glass aquarium. 

 In a short time the anemone left the Bv.ccinum and at- 

 tached itself to the side of the tank ; it next deserted this 

 position and fixed itself on a large stone. After the lapse 

 of some weeks a hermit crab was dropped into the tank, 

 and he was not long there before he walked up to the 

 whelk-shell, and, after a slight survey, backed into it. I 

 suppose this was a state of afiairs the parasite perched on 

 the rock above had long been waiting for ; for it was not 

 long in moving its disk over the top of the small whelk, 

 and before the crab knew where he was, parasite had 

 pitched his tent on the roof of the hermit's house. Where 

 the hermit crab goes, there goes parasitica ; a quiet life it 

 led before, a restless one it has to lead now. But doubtless 

 it knows what is best for it. 



Parasitica, and in the same way Dianthus, Bellis, and 

 some other species, when irritated, will shoot out from all 

 parts of the surface of their bodies, as well as from their 

 mouths, long white filaments to the length of from four to 

 six inches. These filaments, which exactly resemble white 

 sewing-cotton, are believed to be the anemone's weapons of 

 defence. No species is so copiously supplied with them as 

 the parasite, and when very much disturbed a huge bundle 

 is ejected from the mouth. After a time they are all 

 retracted. 



Other species of anemones, as Gem, Strawherry, Dahlia 

 (which we purpose hereafter to describe), never eject these 

 filaments, and from this circumstance 3Ir. Gosse, in 

 " Actinologia Britannica," has named this family of 

 anemones Sagartiada-, to indicate the genera which emit 

 these fleshy cords. The name was suggested by the 

 following passage in Herodotus that describes a singularly 

 primitive style of fighting practised by the Sayartians, 

 who formed part of the army collected by Xerxes on his 

 invasion of Greece. 



There is a certain nomadic race called Sagartians, of Persian 

 extraction and language. They furnish 8,000 horse, but they are 

 not accustomed to carry arms of either brass or iron, except 

 daggers. They use ropes made of twisted thongs. Trusting to 

 these they go to war. The mode of fighting of these men is as 

 follows ; When they engage with the enemy, they throw out the 

 ropes, which have nooses at the end, and whatever any one catches, 

 whether horse or man, he drags towards himself, and they that are 

 entangled in the coils are put to death. — Herod, vii. 84. 



The proportion of doctors to the population in diff'erent 

 countries is given as follows by the Siglo Medico : — France, 

 2-91 per 10,000; Germany, 3-21 per 10,000; Austria, 

 3-41 per 10,000 ; England, 6 per 10,000 ; Hungary', 6-10 

 per 10,000 ; Italy, C-IO per 10,000 ; Switzerland, 7-OG per 

 10,000; United States, 16'24 per 10,000. 



TRICYCLES IN 1883. 



SMALL WHEELS VERSUS LARGE. 



[I HAVE received several letters from a valued correspondent 

 who has read my articles in Knowledge on " Tricycles" — the Eev. 

 J. M. Taylor, of Seer Green Vicarage, Beaconsfield. These letters 

 contain so much of interest on the question of the size of wheels 

 and the weight of machines, and also a statement of the rationale 

 of rubber, so concisely and admirably expressed, that I have asked 

 my correspondent for his kind permission to send extracts from 

 them to Knowledge. Having received the permission, I append 

 them below. — John Browning, Chairman of the London Tricycle 

 Club.] 



" T KNOW not what has been written against small 

 X wheels, but it must be very much to the point if it 

 avails anything against your experience and statements 

 proceeding from it." 



" I agree with large wheels as contrasted with small 

 ichen (he tyres are iron, because the larger wheel has less 

 curvature and larger bearing surface for that reason, and 

 small iron-tyred wheels seem to require iron rails to run on. 

 But rubber on the road is like the camel's spongy foot on 

 sand and stones, it makes a level track, virtually for itself, 

 virtually levelling stones and filling hollows, but this 

 action must be in proportion to its bulk and softness and 

 elasticity." 



"The rationale of rubber seems to me to be thus fairly 

 expressed : — It makes a wheel to serve as a foot. But in 

 order to be so practically, its softness and elasticity must 

 not be compromised by hardness proceeding from adultera- 

 tion, and Viy reduction of its self-accommodating property 

 by reduction of its bulk to the size of a walking-stick. 

 Such sizes may do for a cinder-path, where grip and light- 

 ness are the sole requirements ; but on a road where we 

 require to keep an even course on a surface abounding in 

 bumps and hollows, the good results of rubber depend on 

 quantity and softness with abundance of elasticity." 



" So far as the road is concerned, a large wheel is the 

 nearest rigid substitute for a plane, and is really a clumsy 

 contrivance, for it departs from the principle of a rigid 

 circle and hard tangential plane for an approach to two 

 planes. Whereas the rubber-tyre is a foot, not only accom- 

 modating itself to a true plane, when it finds one, but to 

 irregularities also of all kinds within reasonable limits. 



" Now this principle of the rubber-tyre is not aflected by 

 largeness or smallness of wheels within the limits of size 

 which we use, and it is, therefore, wholly a mistake to go 

 to the large wheels for that which the small one will yield 

 as well. Nay, it will yield it better ; for if we have tyres 

 on small wheels containing as much (say) rubber as would 

 be used in large ones, we shall have a great deal of elastic 

 play of our small wheels, self-accommodation to irregularities 

 of surface, and aVisence of jolting. 



" I thank you for the number of Knowledge. I think 

 your reasoning from facts quite conclusive. 



" I am suti'ering from the very error you are writing 

 against. I moved from a 16 in. to 24 in. steering-wheel 

 without any corresponding benefit, but with the disad- 

 vantage of greatly-increased weight of framework to 

 carry it." 



" I mentioned to you a ' Meteor ' sociable, which is let 

 out at Beaconsfield, with small wheels and ruhliers 1 '- in. 

 diameter. I heard today, by accident, that the tricycle 

 in qviestion is considered the easiest and smoothest 

 travelling of any in Beaconsfield. This testimony is, in 

 its way, as direct and positive as records of 50 or 100 miles 

 would be. It may help your reasoning as being deduc- 

 tion from fact, if you can get information as to other 



