02 



NATURE 



[May 19, iSSi 



arc system, which it necessarily is when the current has 

 to traverse a number of small lights, it has the great 

 advantage of possessing perfect steadiness, which an 

 arc lamp can never rival, and for interior lighting this is 

 of great importance. The cost of carbons constitutes 

 an important item in the expenses attached to electric 

 lighting as now employed, and if we consider that in 

 some incandescent systems the consumption of material 

 is for a considerable period nothing at all, we may still 

 work economically even though using considerably more 

 horse-power to obtain our results. 



Incandescent lamps, however, as at present con- 

 structed, are limited to small lights and a certain steady 

 strength of current, as any sudden increase is apt to 

 break the thin carbon tilanient employed. In addition to 

 this it is necessary to protect the incandescent carbon of 

 such lamps from the influence or access of oxygen, as it 

 would be rapidly consumed b\ even tlie slightest amount 

 of oxygen present. Therefore it must be protected by 

 inclosing it in a vacuum, and it is a matter of consider- 

 able difficulty to produce a sufficiently perfect vacuum to 

 prevent some small quantit\- of free oxygen from coming 

 into contact with the light-giving material. Incandescent 

 lamps are very capricious. Difficulties arise from the 

 extreme thinness and delicacy of the glass employed, 

 leakage from defective sealing or fractures, the liabilit\ 

 of the incandescent material to shake loose in its supports. 



and the great care required in manipulation. The foel 

 lamp is free from these objections, and as in lamps 

 that are purely incandescent, the heat is produced by the 

 cuiTcnt only (the carbon not undergoing combustion by 

 reason of the absence of oxygen), it follows that the 

 incandescent portion cannot attain so high a temper.ature 

 as when the carbon consumes, .and therefore the light 

 must necessarily be of less power than that in the lamp 

 described. The oflices of the Electric Light Agencv in 

 Queen \"ictoria Street arc lighted by this system, and in 

 the workshop two of these lamps t.ake the place of fifteen 

 gas jets with highly satisfactory resuhs. The carbons 

 employed are of 5 mm. diameter, and in length of about 

 I m. The lamp burns for seven or fourteen hours, 

 according to the dimensions of the carbon. 



The Swan lamp is the only purely incandescent lamp 

 that has met with any success in England. The Maxim 

 light, the most successful in America, has not reached 

 here yet. Dr. Draper's house in New York is lit by it. 

 and he is able to nwnipulate his lamps with all the ease 

 and comfort of gas-fittings. Sir William Armstrong, at 

 Craigside, near Newcastle, has utilised a brook to run a 

 dynamo-machine by means of a turbine, and he is able 

 to m.aintain thirty-seven Swan-lights in his house. Mr. 

 Spottiswoode occasion.illy giatifies his friends by illu- 

 minating his rooms with Swan-lights, and the rooms of 

 the Royal Society were so lit at their last sotWc: But such 

 lamps remain luxuries, and nothing more. 



Wherever the electric light has been introduced for 

 internal illumination it has met with considerable favour. 

 It not only lowers the temperature of a gas-lit room within 

 reasonable bounds, but it cle.irs the .atmosphere of vitia- 

 tions, and men work more cheerfully and better. In fact 

 the extra amount of work got out of men is said in some 

 instances to pay for the change. Moreover, since it 

 renders the illumination comparable with that of daylight, 

 it en.ables the aged and the weak-sighted to read and 

 work without spectacles. 



Electric lighting has however passed the experimental, 

 it has now reached the practical stage. 



HO IV TO PREVENT DROWNING 

 T WISH to show how drowning might, under ordinary 

 *■ circumstances, be avoided even in the case of persons 

 otherwise wholly ignorant of what is called the art of 

 swimming. The niunerous frightful casualties render 

 every working suggestion of iniportance, and that which 

 I here offer I venture to think is entirely available. 



When one of the inferior animals takes the water, falls, 

 or is thrown in, it instantly begins to walk as it does when 

 out of the water. But when a man who c.innot "swim"' 

 falls into the water, he makes a few spasmodic struggles, 

 throws up his arms, and drowns. The brute, on the 

 other hand, treads water, remains on the surface, and is 

 virtually insubmergible. In order then to escape drowning 

 it is only necessary to do as the brute does, and that is to 

 ti-ead or w.ilk the water. The brute has no ad\-antage in 

 regard of his relative weight, in respect of the water, over 

 man, and yet the man perishes while the brute lives. 

 Nevertheless any man, any woman, an)' child who can 

 walk on the land may also walk in the water just as 

 re.idily as the animal does, if only he will, aiid that with- 

 out any prior instruction or drilling whatever. Throw a 

 dog into the water and l.e breads or walks the water 

 instantly, and there is no i.r.iginable reason why a 

 human being under like circumstances should not do as 

 the dog does. 



The brute indeed walks in the water instinctively, 

 whereas the man has to be told. The ignorance of so 

 simple a possibility, namely the possibility of treading 

 water, strikes me as one of the most singular things in 

 the history of man, and speaks very little indeed for his 

 intelligence. He is, in fact, as ignorant on the subject as 

 is the newborn babe. Perhaps something is to be ascribed 

 to the vague meaning which is attached to the word swim. 

 ^\■hen a man swims it means one thing, when a dog 

 swims it means, another and quite a ditlerent act. The 

 dog is wholly incapable of swimming as a man swims, 

 but nothing is more certain than that a m.an is capable 

 of swimming, and on the instant, too as a dog swims, 

 without any previous training or instruction, and that by 

 so doing without fear or hesitancy, he will be just as safe 

 in the water as the dog is. 



The brute in the water continues to go on all fours, and 

 the man who wishes to save his life and cannot otherwise 

 swim, must do so too, striking alternately, one two, one 

 two, but without hurry or precipitation, with hand and 

 foot, exactly as the brute does. Whether he be provided 

 with paw or hoof, the brute swims with the greatest ease 

 and buoyancv. The human being, if he will, can do so 

 too, with the further immense advantage of having a 

 paddle-formed hand, and of being able to rest himself 

 when tired, by floating, a thing of which the animal has 

 no conception. Bridget Money, a poor Irish emigrant, 

 saved her own life and her three children's lives, when 

 the steamer conxcying them took fire on Lake Erie, by 

 floating herself, and making them float, which simply 

 consists in lying quite still, with the mouth shut and the 

 head thrown well back in the water. The dog, the horse, 

 the cow, the swine, the deer, and even the cat, all take to 

 the water on occasion, and sustain themselves perfectly 



