IX] SILSOE AND LEIGHTON BUZZARD 133 



which the whole supply of the canal, both for its locks as well 

 as for evaporation and leakage, had to be drawn. Whenever 

 there was a deficiency of water here to float the barges and 

 fill the locks, traffic was checked till the canal filled again ; 

 and this had become so serious that, for a considerable portion 

 of the canal, it had been found necessary to erect steam- 

 engines to pump up the water at every lock from the lower 

 to the higher level. Sometimes there were two, three, or 

 more locks close together, and in these cases a more powerful 

 engine was erected to pump the water the greater height. 

 Up to this time I had never seen a steam-engine, and there- 

 fore took the greatest interest in examining these both at rest 

 and at work. They had been all erected by the celebrated 

 firm of Boulton and Watt, and were all of the low-pressure 

 type then in use, with large cylinders, overhead beam, and 

 parallel motion, but each one having its special features, the 

 purport of which was explained to me by my brother, and 

 gave me my first insight into some of the more important 

 applications of the sciences of mechanics and physics. 



Of course at that time nobody foresaw the rapid develop- 

 ment of railways all over the country, or imagined that they 

 could ever compete with canals in carrying heavy goods. 

 Yet within two years after the completion of the line to Bir- 

 mingham, the traffic of the canal had decreased to 1,000,000 

 tons, while it was 1,100,000 tons in 1837. Afterwards it 

 began slowly to rise again, and had reached 1,627,000 tons 

 in 1900, an exceedingly small increase as compared with 

 that of the railway. And this increase is wholly due to local 

 traffic between places adjacent to the canal. 



In the northern part of the parish, which extended nearly 

 to the village of Great Brickhill, were some curious dry 

 valleys with flat bottoms, and sides clothed with fir woods, 

 a kind of country I had not yet seen, and which impressed 

 me as showing some connection between the geological for- 

 mation of the country and its physical features, though it was 

 many years later when, by reading Lyell's " Principles of 

 Geology," I first understood why it should be so. Another 

 interesting feature of the place, which no one then saw the 



