THE RANGE OF NATURE'S OPERATIONS. 219 



one micron forward in the open ether. It is the hundredth part of the 

 jot (or foiirth-metrot of time), which unit he found it convenient to use 

 in his memoir on the production of double and multiple lines in spectra 

 by perturbating forces acting- on the electrons. (See Sc. Trans. R. D. S., 

 Vol. IV, p. 565.) 



One of the conveniences of the proposed way of representing time 

 is its perfect flexibility. In each investigation we may select as our 

 unit of time that of the whole decimal series which happens to be the 

 most convenient to use in the investigation. In the above-mentioned 

 inquiry it happened that a relatively large unit was the most convenient. 

 In other inquiries the micron, which is 100 times briefer, is a more 

 convenient unit, and in some few, in which very much smaller periods 

 of time were under consideration, the tenth-metret of time was 

 employed. 



The micron of time is the XIV* (fourteenthet) of the third of a sec- 

 ond; that is, the three hundredth part of the billionth ^ of a second. To 

 magnify it till it becomes one second of time is the same process as to 

 magnify the fifth part of the thousandth of a second until it becomes 

 1,900 years, i. e., the whole duration of the Christian era. It is instruc- 

 tive to bear this in mind when dealing with molecular events. 



In dealing with molecular events it is well to conceive a magnified 

 model of what is really going on, in which all lengths are so enlarged 

 and all times so much prolonged as to bring both within the range of 

 what we can conveniently perceive. In order to do this, the magnifi- 

 cation with respect to time will need to be greater than that with respect 

 to space. A good magnification for many purposes is a magnification 

 of all lengths by a uno-ten and a magnification of the durations by 

 either 3 or 6 uno-fourteens." (See Scientific Proceedings R. D, S., 

 Vol. VIII, p. 372, or Philosophical Magazine for October, 1896, p. 381.) 



^ A billion in Great Britain is a million of millions. 



^ The magnification of molecular intervals l)y a nno-ten may be called standard 

 magnification of molecular events; because it means the representing of molecular 

 events which require to be recorded in Group D by a model of them so large that it 

 records them in the corresponding parts of Group 0, the group of magnitudes with 

 which we are most familiar. 



A magnification of molecular magnitudes which is a thousandth or a ten-thousandth 

 part of this standard will often be found useful. On the former of these scales 

 chemical atoms may be represented by beads,- on the other by very fine sand used 

 in hourglasses, while in the standard model the chemical atoms are somewhat like 

 quadrupeds of various sizes crowded together. 



The magnification of the durations by 3 XIV (three uno-fourteens) means that 

 each micron of time becomes a second, so that an event in the molecular world which 

 occupies a fraction of a micron of time is represented by an event of the same kind 

 in our model which occupies the same fraction of a second. This, in the case of a 

 great number of molecular events, brings the events occurring in the model within 

 the range of human perceptions. If the time magnification is by 6 XIV (six uno- 

 fourteens) , a molecular event that occupies some fraction of a micron of time is rep- 

 resented by an event in the model which occupies the same fraction of two seconds; 

 and this is sometimes convenient where we wish to compare molecular motions with 

 the motions of pendulums or of the limbs of animals, since a i)endulum which beats 

 seconds is one whose periodic time is two seconds. 



