January 7, 1898.] 



SCIENCE. 



be less than three right angles, but in this 

 case the total volume of space would still 

 be infinite. Now, this is an hypothesis to 

 be tested by experience. Unfortunately, we 

 cannot triangulate from star to star ; our 

 limits are the two extremes of the earth's 

 orbit. All we can say is that, within those 

 narrow limits, the measures of stellar par- 

 allax give no indication that the sum of the 

 angles of a triangle in stellar space differs 

 from two right angles. If our space is el- 

 liptical, then, for every point in it — the po- 

 sition of our sun, for example — there would 

 be, in every direction, an opposite or polar 

 point whose locus is a surface at the great- 

 est possible distance from us. A star in 

 this point would seem to have no parallax. 

 Measures of stellar parallax, photometric 

 determinations and other considerations 

 show conclusively that if there is any such 

 surface it lies far beyond the bounds of our 

 stellar system. 



Such are the considerations by which it 

 seems to me that speculations on this sub- 

 ject may legitimately be guided. The wise 

 man is one who admits an infinity of 

 possibilities outside the range of his experi- 

 ence, but who in considering actualities is 

 not decoyed by the temptation to strain 

 the facts of experience in order to make 

 them accord with glittering possibilities. 

 The experience of the race and all the re- 

 finements of modern science may be re- 

 garded as showing quite conclusively that, 

 within the limits of our experience, there is 

 no motion of material masses in the direc- 

 tion of a fourth dimension, no physical 

 agency which we can assume to have its 

 origin in regions to which matter cannot 

 move, when it has three degrees of free- 

 dom. Claiming this, we must carry the 

 claim only to the limits justified by actual 

 experience. We have no experience of the 

 motion of molecules ; therefore we have no 

 right to say that those motions are neces- 

 sarily confined to three dimensions. Per- 



haps the phenomena of radiation and elec- 

 tricity may yet be explained by vibration 

 in a fourth dimension. We are justified by 

 experience in saying that the space relations 

 which we gather from observation around 

 us are valid for the greatest distances 

 which separate us from the most distant 

 stars. We have no right to extend the 

 conclusion further than this. We must 

 leave it to our posterity to determine 

 whether, in either way, the hypothesis of 

 hyper- space can be used as an explanation 

 of observed phenomena. 



S. Newcomb. 



REPORT UPON SOME PRELIMINARY EXPERI- 

 MENTS WITS THE RONTGEN RAYS ON 

 PLANTS. 



Since it is a matter of some interest to 

 know what influence, if any, the Kontgen 

 rays would exercise on plants, I undertook 

 a series of somewhat extensive preliminary 

 experiments, to determine what lines of in- 

 vestigation might profitably be carried on 

 should there be marked indications of any 

 response to possible stimuli from this source. 



The lecture room of our botanical de- 

 partment being connected by separate elec- 

 tric wire for the stereopticon, and the wire 

 passing within a few metres of the end of 

 one of the houses of the (^botanical) conserva- 

 tory, the current could be connected with 

 the apparatus in the glass house with little 

 trouble and expense. The connecting of 

 the electi-ic wires with the house was done 

 under the direction of Professor H. J. Ryan, 

 of the Sibley College of Mechanic Arts. An 

 ordinary tin frame rheostat and an App's 

 Coil were loaned by Professor E. L. 

 Nichols, of the physical department, and 

 the Crookes tubes used were of a pattern 

 recommended by Professor Nichols, who, at 

 the beginning of the experiment, set up the 

 apparatus. To him I am indebted! also for 

 advice concerning the use of the apparatus, 

 and also to Professor E. Merritt, of the 

 physical department. 



