lvl 
As long as Boulton and Watt were paid in proportion to the 
savings they effected, it was necessary to ascertain the perform- 
ance of their engines ; but when—at the expiration of their patent 
—they quitted Cornwall, the miners—believing this necessity to 
have ceased—no longer registered the duty, and it immediately ~ 
began to decline. Whatever notice may have been taken of this 
untoward consequence, several years were permitted to pass before 
active measures were taken to arrest it.* In 1811, however, the 
evil had so materially increased that the managers of several 
extensive mines determined to resume the system which had 
served, at once, to determine the claims of the patentees, and as 
a check on their enginemen.t Capt. Joel Lean—from his acquaint- 
ance with mining machinery in general and with the steam-engine 
in particular—was forthwith appointed Registrar and Reporter of 
duty,{ and he and his descendants§ have ably discharged the 
duties of the office from that time to this. When an engine has, 
of a sudden, greatly exceeded its previous performance, and at 
once overleaped several competitors, special trials have sometimes 
taken place ;|| these—when made by qualified persons—have in 
all cases confirmed the accuracy of the Feporter,{1 but less experi- 
enced practitioners have now and then published much greater 
results.** 
The following columns show the number of engines reported 
and their average annual duty as recorded by the original Regis- 
trar, as well as by his son, and grandson, from 1811 to the present 
* Lean, Historical Statement, p. 10. 
+ ‘‘ The first who appears to have been sufficiently alive to the subject, 
‘‘was the late Captain John Davey, of Gwinear, who was the principal 
‘““manager and engineer at Wheal Alfred; and accordingly the first report 
‘appeared in 1811, containing three engines at work on that mine, the 
‘average duty of which was about twenty millions: these engines were 
“at that time reckoned the best in the county. Other mines quickly 
‘followed. In August of that year eight engines were reported, with an 
‘average duty of 15:7 millions; and in December, the number had in- 
‘“ereased to twelve, average duty seventeen millions.” J/bid, p. 10. 
t Ibid, p. 11. 
§ Joel Lean,....the first Registrar,.... died at Camborne in 1812; 
Thomas Lean (his son), the second Registrar, was born at Ludgvan 8th 
February, 1784, died at Crowan 1st June, 1847; : 
Thomas Lean, jun., (son of Thomas), the third Registrar, was born at 
Crowan 26th April, 1827. 
a l Lean, Historical Statement, pp. 20, 31, 58-61, 97-101. Ante, pp. 
, 5A. 
q Lean, Historical Statement, pp. 58-61. Ante, pp. 53, 54. 
** Lean, Historical Statement, pp. 97-101. Anite, pp. 53, 55. 
