1814 

 1815 

 1816 

 1817 

 1818 

 1819 

 1820 

 1821 

 1822 

 1823 

 1824 

 1825 

 1826 

 1827 

 1828 

 1829 

 1830 

 1831 

 1832 

 1833 

 1834 

 1835 

 1836 

 1837 

 1838 



32 

 35 

 35 

 35 

 36 

 40 

 46 

 45 

 52 

 52 

 49 

 56 

 51 

 51 

 57 

 53 

 56 

 58 

 59 

 56 

 52 

 51 

 61 

 58 

 61 



Average duty of the whole. 



19,300,000 

 19,500,000 

 20,600,000 

 20,500,000 

 23,000,000 

 26,500,000 

 25,400,000 

 26,300,000 

 28,700,000 

 28,200,000 

 28,900,000 

 28,200,000 

 28,300,000 

 32,000,000 

 30,500,000 

 32,100,000 

 37,100,000 

 41,700,000 

 43,300,000 

 43,400,000 

 45,000,000 

 46,600,000 

 47,800,000 

 47,800,000 

 46,600,000 

 47,000,000 

 48,700,000 



523 



Average duty of the best en- 

 gine. 



26,400,000 

 32,000,000 

 28,700,000 

 32,400,000 

 41,600,000 

 39,300,000 

 40,000,000 

 41,300,000 

 42,800,000 

 42,500,000 

 42,100,000 

 43,500,000 

 45,400,000 

 45,200,000 

 59,700,000 

 76,800,000 

 77,000,000 

 78,000,000 

 71,100,000 

 85,000,000 

 84,300,000 

 90,900,000 

 91,700,000 

 85,400,000 

 87,200,000 

 84,200,000 



It will appear, by inspection of the duties registered in the preceding ta- 

 ble, that the augmentation of the efficiency of the engines has not been the 

 effect of any great or sudden improvement, but has rather resulted from the 

 combination of a great number of small improvements in the details of the 

 operation of these machines. In these improvements more is due to the suc- 

 cessful application of practical experience than to any new principles de- 

 veloped by scientific research. Mr. John Taylor, in his " Records of 

 Mining," has traced the successive improvements on which the increased 

 duty of engines depends, and has connected these improvements with their 

 causes in the order of their dates. The following results, abridged from his 

 estimates, may not be uninteresting : 



In 1769, soon after the date of the earliest discoveries of Mr. Watt, but 

 before they had come into practical application, Smeaton computed that the 

 average duty of fifteen atmospheric engines, working at Newcastle-on-Tyne, 

 was 5,590,000. The duty of the best of these engines was 7,440,000, and 

 that of the worst 3,220,000. 



In 1772, Smeaton commenced his improvements on the atmospheric engine, 

 and raised the duty to 9,450,000. 



In 1776, Watt obtained a duty of 21,600,000. 



At this time Smeaton acknowledged that Watt's engines gave a duty amount- 

 ing to double that of his own. 



In 1778-'79, Watt reported a duty of 23,400,000. 



From 1779 to 1788, Watt introduced the application of expansion, and raised 

 the duty to 26,600,000. < 



In 1798, an engine by Boulton and Watt, erected at Herland, was reported 

 as giving a duty of 27,000,000. 



This engine, which was probably the best which at that time had ever 



