539 



SCIENTIFIC SIDE-LIGHTS 



Poverty 

 Power 



sede all others, is that of burning coal. This 

 material, like a watch wound up, is matter 

 in a state of power, or in a state of unstable 

 equilibrium, ready to rush into combination 

 with the oxygen of the atmosphere as soon 

 as the initial action is given, and to evolve 

 power in the form of heat until the whole 

 is consumed. It has been proved that on 

 an average four ounces of coal is sufficient 

 to draw, on a railway, one ton a mile. It 

 has also been found by experiment that a 

 man working on a tread-mill continuously 

 for eight hours will elevate one and a half 

 million of pounds one foot high. Now, good 

 Cornish engines will perform the same work 

 by the expenditure of the power of a pound 

 and a half of coal. It follows from these 

 data that about five tons of coal would 

 evolve as much power during its combustion 

 as would be equal to the continued labor of 

 an able-bodied man for twenty years, at the 

 rate of eight hours per day; or, in other 

 words, to the average power of a man during 

 the active period of his life. Providence 

 has therefore stored away in the form of 

 coal, for the use of man, an incalculable 

 amount of mechanical power. Beneath the 

 soil of our own great coal-basins there re- 

 poses power equivalent to the united force 

 of myriads of giants, ready (like Aladdin's 

 genius) to be called into activity by the 

 lamp of science, and as its obedient slave 

 to build cities, to transport palaces, or to 

 remove mountains. There is no other loco- 

 motive power over which man has any pros- 

 pect of control in the least degree compara- 

 ble with this. HENRY Improvement of the 

 Mechanical Arts, Scientific Writings, vol. i, 

 p. 314. (Sm. Inst., 1886.) 



2658. POWER, EXPULSIVE Comets 

 Shot Forth from Stars Proved by Para- 

 bolic Orbits. Every comet or meteor which 

 follows a parabolic orbit possesses a velocity 

 greater than that which the sun's attraction 

 could give it, and it certainly enters the 

 sphere of the solar attraction with a con- 

 siderable original velocity. There is, then, 

 no other way of explaining the interstellar 

 velocities of comets and hyperbolic bolides 

 but by tracing back their course to the time 

 when their substance was projected from 

 a star with a velocity exceeding by several 

 miles per second that with which a body 

 would reach that star if it had been drawn 

 by gravity alone from an infinite distance. 

 FLAMMARION Popular Astronomy, bk. v, ch. 

 3, p. 527. (A.) 



2659. POWER, IMPULSIVENESS A 

 SOURCE OF Readiness and Promptness 

 Achieve Contrasted Advantages of the Re- 

 flective Character. As mental evolution goes 

 on, the complexity of human consciousness 

 grows ever greater, and with it the multi- 

 plication of the inhibitions to which every 

 impulse is exposed. But this predominance 

 of inhibition has a bad as well as a good 

 side; and if a man's impulses are in the 

 main orderly as well as prompt, if he has 



courage to accept their consequences, and 

 intellect to lead them to a successful end, 

 he is all the better for his hair-trigger or- 

 ganization, and for not being " sicklied o'er 

 with the pale cast of thought." Many of 

 the most successful military and revolution- 

 ary characters in history have belonged to 

 this simple but quick-witted, impulsive type. 

 Problems come much harder to reflective 

 and inhibitive minds. They "can, it is true, 

 solve much vaster problems, and they can 

 avoid many a mistake to which the men of 

 impulse are exposed. But when the latter 

 do not make mistakes, or when they are 

 always able to retrieve them, theirs is one 

 of the most engaging and indispensable of 

 human types. JAMES Psychology, vol. ii, 

 ch. 26, p. 538. (H. H. & Co., 1899.) 



2660. POWER LOST IN TRANSMIS- 

 SION Reflection of Light Only Partial In 

 all cases where the light is incident from 

 air upon the surface of a solid or a liquid, 

 or, more generally still, when the incidence 

 is from a less highly refracting to a more 

 highly refracting medium, the reflection is 

 partial. In this case the most powerfully 

 reflecting substances either transmit or ab- 

 sorb a portion of the incident light. At a 

 perpendicular incidence water reflects onlj 

 18 rays out of everj 1,000; glass reflects 

 only 25 rays, while mercury reflects 666. 

 When the rays strike the surface oblique- 

 ly the reflection is augmented. At an 

 incidence of 40, for example, water re- 

 flects 22 rays, at 60 it reflects 65 rays, 

 at 80 333 rays; while at an incidence of 

 89^, where the light almost grazes the 

 surface, it reflects 721 rays out of every 

 1,000. Thus, as the obliquity increases, the 

 reflection from water approaches and finally 

 quite overtakes the reflection from mercury; 

 but at no incidence, however great, when 

 the incidence is from air, is the reflection 

 from water, mercury, or any other substance 

 total. TYNDALL Lectures on Light, lect. 1, 

 p. 17. (A., 1898.) 



2661. POWER, MECHANICAL, IN THE 

 SUN'S RAYS The Noontide Sunshine of 

 Manhattan Would Drive All the Engines of 

 the World. From recent measures it ap- 

 pears that from every square yard of the 

 earth exposed perpendicularly to the sun's 

 rays, in the absence of an absorbing atmos- 

 phere, there could be derived more than 

 one horse-power, if the heat were all con- 

 verted into this use, and that even on such 

 a little area as the island of Manhattan, or 

 that occupied by the city of London, the 

 noontide heat is enough, could it all be util- 

 ized, to drive all the steam-engines in the 

 world. It will not be surprising, then, to 

 hear that many practical men are turning 

 their attention to this as a source of power, 

 and that, tho it has hitherto cost more to 

 utilize the power than it is worth, there is 

 reason to believe that some of the greatest 

 changes which civilization has to bring may 



