32 THE FAIRY-LAND OF SCIENCE. 
hot that it gives, with the exception of that produced 
by electricity, the most brilliant artificial light we can 
get such that you cannot put your eye near it with- 
out injury. Yet if you wanted to have a light as 
strong as that of our sun, it would not be enough to 
make such a lime-ball as big as the sun is. No, you 
must make it as big as 146 suns, or more than 
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 atmos- 
phere 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 into 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 
( lo ! inr rnillionth part of the whole) does nearly all the 
work of our world.* 
* These and the preceding numerical statements will be found 
worked out in Sir J. Herschel's Familiar Lectures on Scien- 
tific Subjects, 1868, from which many of the facts in the first 
part of the lecture are taken. 
