Nov. 30, 1888.] 



SCIENTIFIC NEWS. 



553 



THE MAGIC CHAIN. 



A CURIOUS little thing is to be seen occasionally 

 offered for sale in the streets, and as it is easy to 

 make, and is the subject of a very remarkable optical 

 illusion, it may interest our readers. It consists of two 

 chains, the links of which are crossed, as shown in fig. 1. 

 By holding in one hand the highest ring A, and raising 

 the ring B with the other, if the ring A be dropped it will 

 appear to fall through the ring C, and so through the 

 remaining rings, until it reaches the bottom of the chain. 

 The fall of the ring is really an impossibility, and is only 



The Magic Chain. 



an optical illusion. In raising the right chain the rings 

 are in some measure turned, and the movement is trans- 

 mitted from one ring to the other, so that the first one 

 seems to fall from the top to the bottom of the chain, 

 when, in reality, each ring drops successively. The 

 movements, however, are so rapid that the eye cannot 

 follow them, and receives the impression that the same 

 ring is descending throughout the chain. Fig. 2 is the 

 plan of the two chains of which we have only shown 

 one end. The chain, however, can be made of any 

 length. 



THE VENOM OF SERPENTS; ITS 

 NATURE AND ITS ACTION. 



TV/T LAVERUNE has communicated to Cosmos an 

 ' article on the venom of serpents, which calls for 

 certain remarks. He states that "no serpent is large 

 enough to devour a man, and that if serpents occasion 

 so many deaths they are impelled neither by hunger nor 

 by malice. They bite when they are surprised." 



Now, leaving all doubtful stories out of the question, 

 pythons and boas exceeding 30 ft. have certainly been 

 captured; and if we consider their enormous muscular 



power, we can scarcely doubt their ability to destroy a 

 man. Waterton, in his " Essays," tells us that when in 

 Angustura a Spaniard showed him part of a serpent's 

 skin, " which, judging from its amazing thickness, could 

 not have been less than 70 ft. in length. The colonists 

 have appropriately given to this serpent the name of 

 matatoro, or bull-killer." Making all due allowance for 

 the fact that Waterton did not actually measure, but 

 merely estimated the size of this serpent, such a record, 

 given by an experienced out-door naturalist, makes us 

 doubt whether there may not exist larger specimens 

 of serpents than have as yet been exhibited in our 

 museums. 



Nor can we say that the venomous species never act 

 on the offensive. More than 20,000 persons perish 

 annually in India from the bite of the cobra and of the 

 kerait (Bungarus cceruleus). 



Even in Europe the deaths from snake-bites are not 

 trifling in number. Within six years M. Viand-Grand- 

 Marais collected in the French departments La Loire 

 and La Vendee 321 cases of the bites of vipers, of which 

 sixty-two, or in round numbers one in five, proved fatal. 

 With this proportion our own estimates, based on ob- 

 servations in the south-east of Europe, will fairly agree. 

 At the same time we must bear in mind that the stings 

 and bites of all the less venomous animals are very much 

 affected in their activity by the constitutional state of the 

 sufferer. In this season two cases have been recorded 

 in each of which a man died from the sting of a single 

 wasp. 



The bite of the cobra is, however, hopelessly fatal 

 even to the most healthy and vigorous man, unless the 

 wound can be immediately cut out. The asp by means 

 of which Cleopatra put an end to her life was a closely 

 allied species, Naja haje. At the time when Galen was 

 studying in the school of Alexandria this serpent was 

 used as the public executioner. The condemned 

 criminal was bitten by an asp. This method was more 

 certain, though less rapid, than the electric discharge now 

 introduced in New York. 



The poison of serpents has been the subject of 

 numerous investigatious, both biological and chemical. 

 Inquirers have not been content to observe the effects of 

 accidental bites, but ingenious experimentalists have 

 collected the liquid from the fangs, and have sought to 

 examine the mechanism of its action. In order to collect 

 the poison certain physiologists have proposed to dose 

 the serpent with chloroform and to extract the contents 

 of the venom gland by pressure. This method is scarcely 

 practical, as many of the serpents succumb to the effects 

 of the anEesthetic vapour. The easiest method is that of 

 Sen. De Lacerda. He coils cotton around a stiff rod, and 

 incites the seipent to bite it between the grating of its 

 cage. The cotton becomes charged with the venomous 

 liquid, which can then be obtained by pressure. It is diluted 

 with a little distilled water, and serves for experimental 

 inoculations. If it is not wanted for immediate use it is 

 preferable to keep the saturated cotton and to let it dry. 

 If moistened with a few drops of water a long time 

 after, it resumes all its virtues — or vices. Such a shred 

 of cotton may thus be preserved in a ring, and may serve 

 as the instrument of a "rapid and elegant" suicide. We 

 query both the rapidity and the elegance. The soluble 

 cyanides are far more rapid, and as for the " elegance " 

 of this method of death, our readers may judge from the 

 description of the symptoms which follow the bite of a 

 death-snake. The method which M. Leverune describes 



