HOW THE HEAT IS KEPT UP. 29 



with his income. If, indeed, he be a wise man he will 

 take the opportunity of carrying on his retrenchments to 

 such a point that his expenses shall be even more conveni- 

 ently within his income than they were in the original 

 days of high living. With his moderate establishment, 

 and with an income which is abundant in comparison with 

 that establishment, the owner may feel a comfort and 

 enjoy a genuine prosperity which he never knew in those 

 bygone days that seemed more splendid. He may actu- 

 ally have more money in his pocket and be in a more 

 satisfactory financial condition. 



In like manner when a great amount of sun heat has 

 been radiated into space and lost for ever, the sun accom- 

 modates itself to the altered circumstances by shrinking 

 inwards. Like the prudent man who has suffered a 

 reverse of fortune, the sun when it does shrink takes the 

 opportunity of so far reducing its bulk that, even though 

 it has less heat than it originally possessed, yet that heat 

 so shows itself on the reduced bulk that the orb of day 

 may be a more genial body than ever it was, notwith- 

 standing its apparent losses. 



Matter in the solid state undergoes only a compara- 

 tively small diminution of its volume by its loss of heat. 

 For example, when a cannon-ball heated to redness cools 

 down through 100 degrees of temperature, the shrinking 

 of its volume amounts to but little more than a thousandth 

 part of the whole. No doubt in some small degree the 

 quantity of heat left in the cannon-ball does show to 

 slightly better advantage in the reduced bulk than it 

 would have done had the body remained at its original 

 dimensions. The gain, however, in temperature from this 



