Trials of Implements at Carlisle. 
667 
Particulars and Performances of Darhijs S-Horse-Power Broadside 
Steam Digger, Exhibited hij Messrs. J. and H. McLaren. 
Tlie engine is 8 nominal horse-power, witli single cylinder 9 in. diameter, 
12 in. stroke, 120 lbs. safety-valve pressure in boiler. 
Square Feet. 
Heating surface in fire-box 35 "5 
,, tubes, &c 135 "8 
Total 171-3 
Grate surface, 6 • G4 square feet. 
Gearing. — Engine crank shaft makes 3 "92 revolutions to 1 revolution of 
digger shaft. 
The digger tines are spaced about G in. apart from centre to centre, and are 
contained m 3 frames, which are worked by cranks set at equal angles with 
one another. 
There are 13 tines in the centre frame, and 1-4 in each outer frame, making 
41 tines in all. 
Effective width dug as implement advances, observed as .. 20" 7 ft. 
"Weight of implement (given by Messrs. McLaren) : 
Tons. cwt. qrs. 
Engine, boiler, coals, and water, carried on 4 main) -^q g 
travelling-vvlieels \ 
Frame and discers 117 1 
Total 15 7 3 
4 travelling wheels, each 3 ft. 6 in. diameter, 2-0 in. wide. 
Load on wheels per inch width of tyres, 31G lbs. 
Exixriraents ivith Digger at Carlisle, July 10. 
Mean depth dug 6-07 inches = •506 ft. 
Weight of unmoved earth per cubic foot .. .. = 105 " 1 cubic ft. 
Advance of implement (when spuds are on wheels)) , .^.^o r. 
per revolution of digger shaft j 
Advance of implement per revolution of engine .. "262 ft. 
Average revolutions of engine per minute .. 180 
Advance of implement per minute 47 "5 ft. 
Volume of earth moved per revolution of engine .. 2 • 74 cubic ft. 
Weight do. do. .. .. 288 lbs. 
Mean foot-lbs. of work indicated do. .. .. 5254 ft.-lbs. 
Indicated work in engine cylinder per lb. of earth] 
moved, or height in feet to which earth moved I 
must be raised to represent work done (mean off 
G experiments) ] 
Mean indicated horse-power when working straight) 
ahead I 
18 
Mean indicated horse-power working and turning) 
at ends ( 
28 
26 
2 ft.-lbs. 
7 h.-p. 
Mean indicated horse-power running light over land( 
straight ahead, but with diggers out of gear ..J 
Eatio of power required to move implement without ) 
dii^ging to power required when digging ,. ..\ 
Time occupied for each half- turn at ends of fuiTOws,) ^, . , 
digging at same time (favourable instances) .. \ mmutes. 
575 
