244 EIGHTEENTH CENTURY. PT. in. 



James Watt, 1736-1819, Black had now completed 

 his discovery, and from that time he taught in all his 

 lectures that heat becomes latent or absorbed when a solid 

 is changed into a liquid, or a liquid into vapour. It was 

 about this time that the famous engineer, James Watt, began 

 to study the power of steam, and as Black was his friend, 

 he came to him to help him solve his difficulties. The his- 

 tory of the steam-engine, being the history of an invention, 

 does not strictly belong to our work ; but the use which 

 Watt made of the discoveries about steam is a part of 

 science, and we must therefore find room for a slight sketch 

 of it here. 



James Watt was born at Greenock in 1736; he was the 

 son of a builder and shipwright, and was so delicate as a 

 child that he was kept at home, and learnt reading from his 

 mother, and writing and arithmetic from his father. When 

 at last he was sent to school he found it hard work, for he 

 was slow and thoughtful, and the other children jeered at 

 him for his want of quickness. Everyone knows the story 

 of his being scolded by his aunt for sitting silent a whole 

 hour, holding first a spoon and then a saucer over the steam 

 rising from a kettle, and watching drops of water gathering 

 upon them. It was in this quiet way that little James's 

 mind grew, and it may be an encouragement to slow, plod- 

 ding boys to know that one of our greatest inventors was 

 considered a dull and backward child. 



As he grew older James went up to London, and there, 

 after overcoming many obstacles, which the guilds, or trades' 

 unions of those days, put in the way of all independent 

 workers, he learnt to make mathematical instruments, and 

 then returned to Glasgow, where he began business. Though 

 he was only one-and-twenty he soon became known as a 



