[of The Ether] It Is

I Can Never Satisfy Myself Until I Can Make A Mechanical Model Of A Thing. If I Can Make A Mechanical Model, I Can Understand It. As Long As I Cannot Make A Mechanical Model All The Way Through I Cannot Understand.

In Physical Science A First Essential Step In The Direction Of Learning Any Subject Is To Find Principles Of Numerical Reckoning And Practicable Methods For Measuring Some Quality Connected With It. I Often Say That When You Can Measure What You Are Speaking About, And Express It In Numbers, You Know Something About It; But When You Cannot Measure It, When You Cannot Express It In Numbers, Your Knowledge Is Of A Meagre And Unsatisfactory Kind; It May Be The Beginning Of Knowledge, But You Have Scarcely In Your Thoughts Advanced To The Stage Of Science, Whatever The Matter May Be.

Accurate And Minute Measurement Seems To The Non-scientific Imagination, A Less Lofty And Dignified Work Than Looking For Something New. But Nearly All The Grandest Discoveries Of Science Have Been But The Rewards Of Accurate Measurement And Patient Long-continued Labour In The Minute Sifting Of Numerical Results.

The Vortex Theory [of The Atom] Is Only A Dream. Itself Unproven, It Can Prove Nothing, And Any Speculations Founded Upon It Are Mere Dreams About Dreams.

Can You Measure It? Can You Express It In Figures? Can You Make A Model Of It? If Not, Your Theory Is Apt To Be Based More Upon Imagination Than Upon Knowledge.