352 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



to explain the continued working of physical 

 phenomena, or the continuance of change in the 

 universe, the existence of some process of recur- 

 rence is absolutely essential. The particular ma- 

 terial that is utilized for the development of fresh 

 suns or centres of heat must be the cooled-down 

 or dead material of former suns. For, if this were 

 not the fact, there would be a continual accumu- 

 lation of the matter of extinct or useless suns in 

 the universe, and processes of renewal and main- 

 tenance of the energy of the universe would come 

 to a deadlock in the absence of matter to operate 

 upon. It therefore becomes absolutely necessary 

 to show, in any attempt to explain the continued 

 working of physical phenomena under present 

 causes, how the material of extinct suns can — in 

 accordance with recognized dynamical principles 

 — be made available for the development of fresh 

 suns (or centres of heat). This conclusion would 

 seem to evolve itself naturally on the basis of the 

 deductions following from the physical theory of 

 gravitation — in regard to the motion of the stars 

 taking place in straight lines, which involves col- 

 lisions and an alternating renewal and loss of 

 heat. This appears on broad principle the only 

 conceivable way in which there should be recur- 

 rence, under the condition that the same matter 

 should be used again. On account of the rela- 

 tively enormous area of free space, compared with 

 the relatively very minute portion of space oc- 

 cupied by each star, a stellar sun would, in the 

 course of its proper motion in a straight line, 

 probably as a rule traverse an immense distance 

 before an encounter, and thus have time to cool 

 down before the renovation of its heat by a col- 

 lision ; the dead or used-up material of former 

 suns being thus available for fresh suns. 



There is one point in connection with this 

 subject that may be worth noticing: The sun, 

 as is known, is giving off an enormous amount of 

 energy in the form of heat into the ether of space, 

 no less than about 1,720 foot-tons of energy being 

 thrown off from every square foot of the sun per 

 second. Can it be imagined that this enormous 

 total of energy can be given off in a particular 

 direction — i. e., from the sun — without any re- 

 action in the opposite direction ; or would it be 

 thought that, if the sun were emitting all this 

 energy from one side only, there would be no re- 

 action in the opposite direction ? To us it seems 

 incredible, whatever the constitution of the ether 

 may be imagined to be, that there should be no 

 reaction at all by this enormous total of energy 

 thrown off. 1 Admitting that there is a slight re- 



1 We do not mean to infer that the reaction due to 



action, then it is probable that it would not be 

 absolutely equal all round the sun, owing to ac- 

 cidental irregularities in the temperature and radi- 

 ating power of the materials of the sun's surface. 

 If this reaction were only a few grains per square 

 foot (due to 1,720 foot-tons of energy thrown off 

 per square foot per second), the resultant or un- 

 balanced reaction, owing to irregularities in the 

 distribution of the sun's heat and radiating power, 

 might amount to a considerable total quantit}^ 

 owing to the enormous area of the sun. This re- 

 action, even if relatively small, might, in acting 

 for ages (millions of years), in the end sensibly 

 affect the proper motion of the sun ; or this 

 might be a cause having some influence on the 

 proper motion of the stellar suns, in addition to 

 the repulsive action of the heat generated by the 

 mutual collisions. 



In the absence of any explanation of the 

 mechanism of gravity, or idea of the nature of gra- 

 vific energy, it naturally becomes impossible to see 

 how heat once dissipated in the ether could ever 

 be recovered again, or how heat-energy derived 

 I from gravific energy could ever be reconverted 

 into gravific energy. But when it comes to be 

 recognized (as it logically and inevitably must) 

 that gravific energy resides in a medium pervad- 

 ing space, and that therefore this medium is neces- 

 sarily immersed in the ether or heat-conveying me- 

 dium, then we have data for new conclusions. It 

 appears clear, or almost a necessary deduction, 

 that the waves of heat cannot be conveyed through 

 the gravific medium (in which the ether is im- 



radiation is the canse of the motion of the radiometer, 

 as we think there are grounds for believing; that (in 

 the case of the relatively extremely feebte heating of 

 the radiometer) it would not be a sufficient cause to 

 produce the motion, or probably any measurable ef- 

 fect. There can be little doubt that the effective cause 

 of the motion of the radiometer has been quite suc- 

 cessfully traced to the action of the molecules of 

 the residnal gas, as shown by Mr. Johnstone Stoney. 

 This, however, by no means proves that there is 

 no reaction by radiation. In considering the reaction 

 in the case of the sun, the relatively enormous value 

 of the energy continually thrown off from its surface 

 (amounting to thousands of horse-power per square 

 foot) must be duly realized. It may be estimated 

 that a portion of the sun's surface, equal in size to 

 the disk of an ordinary radiometer (say a quarter 

 of a square inch in area), is throwing off a wave- 

 energy equal to twelve horse-power. A vertical col- 

 umn of ether of this sectional area, situated on the 

 sun, is therefore transmitting the same energy as the 

 belt of a twelve-horse steam-engine. Can it be im- 

 agined that it can do so without any reaction at all? 

 Consider, also, the millions of square miles of the 

 sun's surface, each minute portion of which is throw- 

 ing off this same energy. 



