Sept. 21, 1888.] 



SCIENTIFIC NEWS. 



319 



regard it as having any very extensive application. In 

 many cases the religious ideas of the lower races of men 

 have been greatly influenced by the phenomenon of sleep. 



" Some say that gleams of a remoter world 

 Visit the soul in sleep — that death is slumber, 

 And that its shapes the busy thoughts outnumber 

 Of those who wake and live — I look on high ; 

 Has some unknown omnipotence unfurled 

 The veil of life and death ? Or do I lie 

 In dream, and does the mightier world of sleep 

 Spread far around and inaccessibly 

 Its circles ? " 



— Shelley, " Mont Blanc." Lines written in the 

 Vale of Chamouni, Part 3. 



In sleep the body lies as it were dead ; but the mind is 

 often active, and the savage dreams as we do that when 

 his body is asleep the mind wanders away to visit absent 

 fiiends and distant regions. Hence he naturally con- 

 cludes that he has a spirit which can leave the body. 

 Hence also to him dreams have an importance and reality 

 which we can hardly appreciate. Mr. M. Thurm tells 

 us that when he was travelling in Guiana, his head boat- 

 man one morning insisted on thrashing one of the men 

 because he dreamt he had been impertinent to him the 

 night before. Hence to be unexpectedly woke up is in 

 the eyes of some of the lower races of man a real danger. 

 In a recent work on Burmah it is stated that an English 

 magistrate rendered himself very unpopular by waking 

 a native official in the middle of his siesta, or mid-day 

 sleep. The natives argued in this way. The poor man 

 always sleeps from 12 to 2. During this time his spirit 

 wanders away, and often only comes back just before 2. 

 It is now 1. Who can say where the spirit is ? It may 

 be miles away. It is barbarous to wake up a man's 

 bo d when the spirit may be at a distance. The poor 

 wife was, it is said, terribly alarmed. In other cases 

 dream thoughts were regarded as special inspirations, as 

 in the beautiful verses of Job : — " In dreams, in visions 

 of the night, when deep sleep falleth upon man, in 

 slumberings upon the bed;" "Then God openeth the 

 ears of men, and sealeth their instruction." 



Our own sovereigns are still crowned on a stone, the 

 Lia Fail or Stone of Destinjr, which is said to have been 

 the pillow on which the patriarch Jacob slept at Bethel 

 when he saw " the ladder set up on the earth, and the 

 top of it reached to heaven, and behold the angels 



■ending and descending on it." It was carried to Ire- 

 i, then to Iona, subsequently to Scone, and brought 

 to England by Edward I., though some Irish antiqua- 

 ries maintain that the true Lia Fail is the upright stone 

 which stands on the hill of Tara. We all remember 

 the significance attached by Joseph's parents and brethren 

 to his dreams ; as well as the political importance of 

 Pharaoh's dream, which Sir Samuel Baker has recently 

 attempted to explain by supposing that the Abyssinians 

 had dammed up the Atbara river. 



Moreover, the analogy between sleep, and that last 

 long sleep death, could hardly fail to strike the savage. 

 In classical mythology we are told that Mars the god of 

 death, and Somnus the god of sleep, were both children 

 of Nox, the goddess of the night. But as the savage 

 every morning saw his friend awake from sleep, it was 

 not unnatural that he should imagine that they might 

 also arise from the tomb. Moreover, in confirmation of 

 this the spirits of his departed relations often visited him 

 in his dreams, and hence he readily adopted the idea that 

 we have a soul which survives, or may survive, the body. 

 (To be continued.) 



THE ELECTRICAL TRANSMISSION OF 



POWER. 



A Lecture Delivered by Professor Ayrton, F.R.S., etc., 



BEFORE THE BRITISH ASSOCIATION, ON SEPTEMBER 8tH, 

 AND RE-DELIVERED TO THE WORKING-CLASSES OF 



Bath, on September 13TH, 1888. 

 XllT'HAT is power, and why should we wish to transmit 



" it? Power has one very definite meaning in science, 

 and several rather vague meanings in practice. We 

 speak of a powerful athlete, the power of the law, we 

 sing of the power of love, we say knowledge is power, 

 and so on, using the word in several different senses. 

 Now in spite of the fact that a general audience feels a 

 little anxious as to what troubles may be in store for it 

 when a lecturer begins by being painfully exact, my 

 telling you that by power an engineer understands the 

 rate of doing work will not, I hope, make you fear that 

 my remarks will bristle with technicalities. 



When you walk upstairs you exert power, only per- 

 haps the one-twentieth of a horse when you go up slowly 

 talking to other people. But when you run upstairs 

 because you have forgotten something that you intended 

 to bring down, then your exertions represent perhaps 

 the one-tenth of a horse power. You only get to the top 

 of the stairs in either case, but the breathless sensation 

 of running fast upstairs tells you that the more quickly 

 you go the harder you are working. A person exercises 

 power in the engineer's sense when he exerts him- 

 self physically, and the greater the exertion the greater 

 the power. The exercise of power by the ruling classes, 

 however, is unfortunately not necessarily accompanied 

 by any exertion, physical or mental. 



Probably the most familiar example of exerting power 

 at a distance, that is of transmitting power, is pulling a 

 handle and ringing a bell in another room. I pull the 

 handle, exerting myself slightly, and as the result the 

 bell at the other end of the platform rings. Were not 

 this such a very familiar operation I would call it experi- 

 ment No. 1. You have doubtless ,all of you performed 

 this experiment several times to-day, and what is all- 

 important with an experiment, performed it successfully. 



And yet it was not until just one hundred years ago 

 that it dawned on people that if one person, A, wanted 

 to attract the attention of another person, B, the place 

 where the bell ought to sound was where B was and 

 not where A was. Indeed, in many English villages 

 down to the present day, the knocker principle of 

 attracting attention is alone resorted to, without the re- 

 sult which you may remember happened when Mr. 

 Pickwick was staying in Bath at lodgings in the Royal 

 Crescent, and Mr. Dowler undertook to sit up for Mrs. 

 Dowler, but "made up his mind that he would throw 

 himself on the bed in the back room and think — not 



sleep, of course Just as the clock struck three 



there was blown into the crescent a sedan-chair with 

 Mrs. Dowler inside borne by one short fat chairman and 

 one long thin one. . . . They gave one good round double 



knock at the street door ' Knock again, if you 



please,' said Mrs. Dowler from the chair. * Knock two 

 or three times, if you please.' The short man stood on 

 the step and gave four or five most startling double 

 knocks of eight or ten knocks apiece, while the long 

 man went into the road and looked up at the windows 

 for a light. Nobody came. It was as silent and dark as 

 ever." But the tall thin man, you may remember, " kept 

 on perpetually knocking double knocks of two loud knocks 



