44 Presidential Address 



ary as their propounders think. I see a 

 way to retain the old and yet embrace 

 the new, and I urge moderation in the 

 uprooting and removal of landmarks. 



And of these the chief is Continuity. 

 I cannot imagine the exertion of mechan- 

 ical force across empty space, no matter 

 how minute; a continuous medium seems 

 to me essential. I cannot admit dis- 

 continuity in either Space or Time, nor 

 can I imagine any sort of experiment 

 which would justify such a hypothesis. 

 For surely we must realise that we know 

 nothing experimental of either space or 

 time, we cannot modify them in any 

 way. We make experiments on bodies, 

 and only on bodies, using "body*' as an 

 exceedingly general term. 



We have no reason to postulate any- 

 thing but continuity for space and time. 

 We cut them up into conventional units 

 for convenience sake, and those units 

 we can count; but there is really nothing 

 atomic or countable about the things 

 themselves. We can count the rotations 

 of the earth, or the revolutions of an 



