■K) 



KNOWLEDGE 



[Nov. II, 1881. 



will K'o^l'y P")' tbo money. Ho would most probably not refuso 

 even if there were two thonsand C(|iml chances, ond the prize were 

 still but £1,000, though the real viiliio of the ticket would bo but 

 10.1. If, however, yon neked him to pny £1 for the chnnce of Retting 

 £1,000 if n tossed coin comes up head eight times running, ho will 

 reject (probably with ridicule) tlio idea of accepting it. Yet in 

 reality the offer is a far better one than the other. Ho ought to par 

 very nearly .C2 for the chance ofTored him for £1 (the ciact valneof 

 till- chance is£l. 19s. OJd.). Or the " eight times running " might bo 

 changed to " nine times running" if tho £1,000 prize were increased 

 to £1,03-1, and the second offer would then bo as fair as tho other. 

 Hut the game gambler who thinks ho is quite likely, owing to his 

 luck, to draw the right ticket out of a thousand, would utterly 

 despair of tossing head nine times running. 



" Inxeeaskd knowledge confers an increased feeling of duty, and 

 increased power to perform it." — ilaudsley. 



The Cedars op Lebaxon. — The Vienna I'olitische Correspondem 

 says : — Tho once famous cedar forest of Lebanon, formerly so ex- 

 tensive, has dwindled do^vn to the dimensions of a mere thicket, 

 numbering about 40O trees. To save it from complete destruction 

 and preserve it at least in its present extent, Kustem I'asha, the 

 Governor-General of the Lebanon, has issued a special ordinance, 

 containing a series of stringent regulations calculated to check, if 

 not quite put a stop to, the vandalism and carelessness of most 

 travellers. It is expressly forbidden to put np tents or other kinds 

 of shelter within the district of the trees, or to light fires or to cook 

 any provisions in their vicinity. No one is allowed to break off a 

 bough or even a twig from the trees. It is forbidden to bring any 

 beasts of burden, be they horses, mules, asses, or any other kind of 

 animal, within the district. Should oxen, sheep, goat, or other pas- 

 turage cattle be found within the prescribed limits, they wiU be 

 irredeemably confiscated. 



Professional Astronojiers and Popular Astronoits'. — Wc are 

 inclined to doubt whether the official chiefs of great observatories 

 are, as a rule, the persons best fitted to write treatises on popular 

 astronomy. Ttis not that they are unwilling to deal with astronomy 

 in a popul.ir manner. On the contrary, they are apt to adopt too 

 familiar and condescending a tone, as if writing for children. But 

 in reality, their astronomical labours, whether in the observatory or 

 in the calcnlating-room, are not adapted to give them that know- 

 ledge of the general science of astronomy, without which no man 

 can present a.stronomical truths at once simply and effectively. 

 Their work bears the same relation to the real living astronomy of 

 men like tho Herschcls that land-surveying bears to geology as 

 dealt with by a Button, a Playfair, or a Lyell. They find more 

 interest, as a rule, in the correction of a star's place by the tenth of 

 a second of arc than in the inquiry into the star's attributes as a 

 sun. A pcrturliation affecting the moon's position by the hundredth 

 part of her diameter is more important to them than telescopic 

 evidence of the most tremendous changes in the moon's surface 

 would be. In fine, their way of viewing the heavenly bodies some- 

 what resembles the way in which a certain Senior Wrangler is said 

 to have viewed Snowdon, who, when asked if he had climbed that 

 mountain, replied that he had not, because a neighbouring hill was 

 equally suit-able for trigonometrical purj^oses- The astronomy thus 

 taught differs as widely from the astronomy of the Herschels as a 

 series of anatomical plates differs from the Venus of Milo or the 

 Theseus and Ilyssus of the Parthenon. 



Toe Induction Balance applied to Si'kgery. — It was stated in 

 the Timea of Aug. 5 that the place of the bullet in President 

 Garfield's body had been localised by tho use of tho induction 

 balance. The i>ost-mortem examination seems to have shown that 

 the diagnosis was incorrect. Tho Times Correspondent at the Paris 

 Electrical Exhibition makes the following remarks on the subject, 

 which are interesting as including a concise and sufficiently simple 

 account of the method in question. "I am convinced," he says, 

 " that if tho experiments were conscientiously carried out there 

 conld be no error. A remarkable confirmation of the utility of the 

 apparatus as a means of diagnosis has just come to my notice, but 

 1 will first give a short account of the action of the instrument. A 

 current of electricity is passed through two coils of insulated wire, 

 which are kept apart. The current is rapidly made and broken by 

 clockwork. Above each coil is a second similar coil of insulated 

 wire, and every time that a current is made or broken in the first 

 pair of coils a second current is induced in the secondary 

 coils. These secondary coils are connected together and to a 

 telephone, and the currents induced in cither coil tend to 

 produce a noise in tho telephone. But these coils arc so 

 connected as to induce currents in opposite directions in the tele- 

 phone, so that under ordiuary circumstances they destroy each 



other, anil no noise is heard in the telephone. If, however, a piece 

 of metal be placed inside one of tho coils, the character of the 

 induction is changed in that coil, and the balance is destroyed, so 

 that a noise is heard in the telephone. The amount of noise depends 

 upon the form, mass, and conductivity of the metal placed inside. 

 By choosing pieces of metal all of the same tize. but differing in 

 their composition, it is possible to compare tho conducting powers 

 of the metals. A long scale of metal, wedge-shaped, is moved along 

 above the coil which does not contain the metal to bo tested, until 

 the thickness of the wedge over one coil is sufficient to balance the 

 metal inside thcothercoil. Thereadingof the scale on the wedge then 

 gives a measure of the conductivity. Some most astonishing results 

 have been thus obtained. It is found that pure copper electrically de- 

 posited has a conducting power far greater than the copper of com- 

 merce, the difference being far greater than was generally supposed. 

 I will now describe the experiment which has just been completed. 

 Mr. Elisha Gray, of America, whose name is so well known in con- 

 nection with the telephone and the harmonic telegraph, was a 

 disbeliever in the utility of the induction balance as a surgical 

 appliance. Ho said to Professor Hughes, ' Thirty years ago, when 

 working at some metal-work, a filing of iron entered my finger; the 

 more I tried to extract it the deeper it went in. I believe it is still 

 there, and if your instrument is of any value, you ought to be able 

 to tell mo in which finger it is.' The presence of bone or flesh in 

 the coil of the balance wonid produce no effect ; a metal or other 

 conductor is necessary. Professor Hughes tested Mr. Gray's fingers ; 

 none of them gave any sound until he came to the forefinger of the 

 right hand, when the balance of the coils was quite destroyed, and 

 a noise was given out. This was the very finger in which the filing 

 was buried thirty years ago. I need hardly say that Mr. Gray was 

 completelj' convinced." 



■WE.\TnER Forecasts. — That the daily forecasts issued from the 

 Meteorological Office are often wrong I need not say. \\Tiy they 

 are so is simply because general disturbances in the atmosphere 

 only are taken into consideration, local disturbances being ignored. 

 And so long as the forecasts are based solely upon the distribution 

 of barometrical pressure this cannot be otherwise. When there is 

 no distinctly-developed area of high or low pressure lying over the 

 country or approaching our shores, the forecasts must be made at 

 random, for the observer has nothing whatever to guide him in his 

 prediction. He may say "wind light and variable." or "calm," or 

 " weather unsettled " ; but such forecasts are liable to falsification 

 in many districts through the operation of local influences. A little 

 hurricane may start np in one spot, rain m.ay pour in another, and 

 a thunderstoi-m may burst over a third, all unexpectedly, and the 

 observers in the Meteorological Office could not possibly have been 

 expected to warn the afflicted districts. I think, then, the import- 

 ance of local meteorology cannot be exaggerated. The distribution 

 of rainfall over the British Isles sufficiently shows the potency of 

 physical conditions, but a more striking example is found in the 

 fact that within a radius of twelve miles around Somersham Rail- 

 waj- Station (Huntingdonshire) hailstorms are so frequent and 

 destructive that all the insurance companies charge double the 

 ordinarj' rates per acre on crops growing within that district. 

 Violent winds, too, are often due to local causes. An instance of 

 this came undtr my notice some years ago in the Isle of Man, when 

 a violent gale blew over Ramsey from the westward, the air a couple 

 of miles to the north being almost still all the time. The storm 

 rushod along the base of North Barmle, lashing the bay into foam, 

 and apparently becoming dissipated out at sea. The afternoon 

 on which this occurred was bright and almost cloudless, 

 and the storm maintained its fury for several hours. Such 

 local disturbances may be quite as destructive as more 

 general ones, and forecasts, to be of any practical use, onght 

 certain!}- to take cognisance of the causes which produce them. To 

 render forecasts as reliable as onr present knowledge can make 

 them, I would suggest that a local obscr\-er be appointed in each 

 district to act in concert i\-ith the Meteorological Office, and to base 

 the forecasts upon the information and charts supplied by that 

 office, su]iplemcnted by his own knowledge of local conditions and 

 influences. Every district has its system of natural weather signs 

 dependent upon its physical features, and experienced farmers, and 

 others who have given attention to them, can predict tho weather 

 with far greater certainty than the functionaries in London. There 

 was a time when natural signs were our only aid to a foreknowledge 

 of the weather, but since the invention of telegraphy and the con- 

 sequent discover}- of cyclonic movements in the atmosphere, the 

 cat has been discarded and the barometer put in her place. Why 

 not use both ? Theoretical meteorology, so to call it, determines 

 the general distribution of wind and weather over tho country ; 

 local meteorolog}-, the p.articular kind of weather in a district. The 

 one is tho complement of the other ; and in order to obtain the best 

 result they should be used accordingly, the one supplying what tho 

 other lacks. — J. A. VTestwood Oliver in the " Times." 



I 



