September 12, 1902.] 



SCIENCE. 



421 



shows that what he denominates the 

 'modulus of the gas,' the product of two 

 measurable factors for all gases, is a con- 

 stant, Wood finds no difficulty in deter- 

 mining the physical characteristics defining 

 such an ether with at least approximate 

 accuracy. He finds them, as would natu- 

 rally be expected, most extraordinary, as 

 must needs be in a gas transmitting vibra- 

 tions at the rate of nearly two hundred 

 thousand miles a second. liis conclusions 

 are thus expressed : 



A medium which has density such that a 

 volume of it is equal to about twenty vol- 

 umes of the earth would weigh one pound ; 

 whose tension is about 1.1 pound on the 

 square mile ; whose specific heat is 46X10^^, 

 water being unity— would 'satisfy the re- 

 quirements of nature, in respect to trans- 

 mission of heat-energy and light. This 

 conclusion from facts of observation and a 

 probable theory differs from Herschel's re- 

 sult in giving a high value of specific heat, 

 rather than of tension ; substituting a more 

 probable for an entirely improbable con- 

 clusion. This extraordinary but always es- 

 sential element of the universe, it is found, 

 must have a practically uniform tension 

 and density throughout space, changing lit- 

 tle between the surface of a star and the 

 depths of infinity. It at once follows, we 

 further conclude from Wood's data, that 

 if the ether be of limited quantity, at a 

 finite distance from the center of attraction 

 of the universe it must have a definite limit, 

 as of a fog-bank, out of which no ray of 

 light and no stream of heat-energy can 

 pass to other worlds. From Wood's strik- 

 ing yet simple analysis we may derive thus 

 the conclusion that, should it prove correct, 

 there may exist other universes than ours, 

 from which no heat or light or other ethe- 

 real messenger may come to us, but yet that 

 it is possible that, some day, two universes 

 may come together, to unite as one or, in 

 inconceivable violence of world-collision, to 



disperse into a single nebula, subsequently 

 to condense again into a single universe. A 

 runaway star from outer space may un- 

 expectedly appear to cause similar results. 



At the height of 127 miles, the atmos- 

 phere would have the density of such an 

 ether, and this constitutes a measure of the 

 altitude of the atmosphere in close accord- 

 ance with a variety of other determinations 

 on othey and different bases. Everywhere 

 the ether is practically diathermous, non- 

 resisting, and constant in all physical prop- 

 erties. 



An assumption made by Wood was that 

 of the temperature of space, taken by him 

 at 20° P. (11.1° C.) above absolute zero, 

 not far from the temperature of solidifica- 

 tion of hydrogen. But no important 

 change that could be accepted as consist- 

 ent with our knowledge of the temperature 

 of the interstellar space would greatly 

 alter the conclusions reached; nor, in fact, 

 would any probable admissable assump- 

 tion of an independent measure of the 

 'modulus' of this wonderful gas. It is, 

 however, probable that this intensely se- 

 ductive case is not yet closed. 



X. 



The opportunities of the investigator and 

 of the collaborator are beyond our recog- 

 nition, and probably, in our present state 

 of incomplete evolution, even our concep- 

 tion. They may certainly be expected to 

 furnish problems, indefinitely, for research 

 in all fields and for all the immediate fu- 

 ture of science. The resolution of all the 

 recognized sciences, and of possibly as yet 

 unclassified or even unsuspected sciences, 

 into one great system is a final problem to 

 be approximated with the passage of the 

 centuries. 



That such an unlimited range is per- 

 mitted in the work of the man of science 

 is easily seen. In the first place, man, from 

 the beginnings of scientific study and in- 



