32 THE FAIRY-LAND OF SCIENCE. 
146,000,000 times as big as our earth, in order to get 
the right amount of light. Then you would have a 
tolerably good artificial sun ; for we know that the 
body of the sun gives out an intense white light, just 
as the lime-ball does, and that, like it, it has an atmo- 
sphere of glowing gases round it. 
But perhaps we get the best idea of the mighty 
heat and light of the sun by remembering how few of 
the rays which dart out on all sides from this fiery 
ball can reach our tiny globe, and yet how powerful 
they are. Look at the globe of a lamp in the middle of 
the room, and see how its light pours out on all sides 
and jnto every corner; then take a grain of mustard- 
seed, which will very well represent the comparative 
size of our earth, and hold it up at a distance from the 
lamp. How very few of all those rays which are 
filling the room fall on the little mustard-seed, and 
just so few does our earth catch of the rays which 
dart out from the sun. And yet this small quantity 
(njW-millionth part of the whole) does nearly all the 
work of our world.* 
In order to see how powerful the sun's rays are, 
you have only to take a magnifying glass and gather 
them to a point on a piece of brown paper, for they 
will set the paper alight. Sir John Herschel tells us 
that at the Cape of Good Hope the heat was even 
so great that he cooked a beefsteak and roasted some 
eggs by merely putting them in the sun, in a box 
with a glass lid! Indeed, just as we should all be 
* These and the preceding numerical statements will be found worked 
out in Sir J. Herschel's ' Familiar Lectures on Scientific Subjects.' 1868, 
from which many of the facts in the first part of the lecture are taken. 
