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between known and unknown, which for me has always had peculiar 
temptations. I venture to think that the greatest scientific problems of 
the future will find their solution in this borderland, and even beyond; 
here, it seems to me, lie ultimate realities, subtle, far-reaching, wonderful.” 
The developments of the last few years have demonstrated that no 
truer prophecy was ever uttered, and the prophet Crookes has lived to 
witness and to take a part in its fulfillment. 
The importance of the present rejuvenation of physical science does 
not consist alone in the abundance of the harvest. There have been 
abundant harvests in the past. Consider the decade which closed one 
hundred years ago. In 1798 Rumford boiled water by friction. In 1799 
Davy melted ice by friction in a vacuum and Laplace published his work 
on mechanics. In 1800 Volta constructed the Voltaic pile, Nicholson and 
Carlisle decomposed water, Davy discovered the properties of laughing 
gas, and Herschel discovered dark heat rays. In 1801 Piazzi discovered 
the first asteroid, Ritter the chemical rays, and Young the interference of 
light. In 1802 Wedgewood and Davy made sun pictures by the action of 
light on silver chloride, and Wollaston discovered dark lines in the sun’s 
spectrum. In 1808S Malus discovered polarization by reflection, Gay 
Lussac the combination of gases by multiple volumes, and Dalton the law 
of multiple proportions. 
So great was the exhilaration and satisfaction produced by these dis- 
coveries that many scientists of that period appear to have become infected 
with something akin to the “sixth decimal” delusion. “Electricity,” wrote 
the French scientist Haiiy, “enriched by the labor of so many distin- 
guished physicists, seems to have reached the term when a science has no 
more important steps before it, and only leaves to those who cultivate it 
the hope of confirming the discoveries of their predecessors and of casting 
a brighter light on the truths revealed.” A statement which was almost 
immediately followed by the discoveries of Oersted, Ampere, Seebeck and 
Faraday. <A statement which has been followed by the telegraph, the tele- 
phone, the dynamo, the motor, the electric light, the electric railway, the 
Roentgen rays, and the wireless telegraph and telephone. 
If anyone today is disposed to criticise the men of science of other 
times because of their limited view, their complacent opinions and their 
intolerance of all that did not agree with theories they considered estab- 
lished, let him first read and ponder over what One spake about motes and 
beams. 
