THE FORCE THAT DRIVES THE WORLD.

Taranaki Daily News, Volume LIV, Issue 6, 1 July 1911, Page 9

THE FORCE THAT DRIVES THE WORLD.

SUNBEAMS AND SUNLIGHT. How is it that we can see the sunbeams? How is it that we can see the stars? Professor J. J. Thomson has been explaining at the Royal Institution in a series of charming lectures on the sun, the marvellous force from which all life and power come. We see the sunbeams and the sunlight because the sun gives out an enormous amount of what we call radiant energy. All bodies of a temperature above the absolute zero give out radiant energy, but that energy cannot be detected by the eye until the temperature has Teached 400 or SOOdeg. The stars are enormously hot, so we can see their light, but they are such unthinkable distances away that only an indefinitely re-fined-instrument, called the radiometer, invented by Sir William Crooks, can detect their heat.

The energy given off by the sun is vaster than anything else that we can imagine. AVhen it is shining upon our earth, the sun is emitting energy equal to 7000-horse-power per acre. If we could collect this energy, we should have power enough to do ail the mechanical work of the world.

How hot, then, is the sun! Various calculations have been made, but Professor Thomson states that the most accurate is that which places the temperature at G,Ooo,oOOdeg. To think- what that means, we have only to remember that the average heat of the human body is 98deg. If wo get much hotter than that we are said to have a high temperature, and if wo reach lOSdeg. our lives are in grave danger. If the heat of the sun, on reaching the earth, is equal to 7000 homo-power per acre, what must be the energy in the sun itself? This calculation, "too, Professor Thomson has worked out for us. It is equal to 45,000 horse-power per square inch. Our sunlight is cooled for us. Every sunbeam that dances through our window has travelled over 00,000,000 miles, first, through airless space, then through our cool, vaporous atmosphere. Now that all the'world knows of radium and uranium, which gives off heat' and light without any noticeable decline, many people fancy that the sun must be composed of these element*. But kng,i-,tlm last their time is short in comparison with the vast age of the Mm The only theoiy on thu point with which Professor Thomson can agree is that the sun derives its heat by thrink-