Volume Eleven - Pre-Victorian to the Present Day - some more aspects - The Steam Navvy and the Dock Extension of 1883 . . .

For depreciation, repairs, and interest on capital, about £1. per day must be reckoned, being arrived at from £3. 10s. to £4. per day.

The total cost of the machine weighing 32 tons is about £1,250., namely, £1,175. price at the works, and £75. for carriage and erection on the site of the excavation ;  but in many cases the amount allowed for erection can be considerably reduced :

This amount may be considered to be well over the ark. Allowing, therefore, 300 working days in the year, and deducting two days per month for stoppages through bad weather, about 270 available days will remain.

The amount to be reckoned under the above items will therefore be 18s. 6d. per day, or about ⅓d, per cubic yard, or say from ½d. to 1d. per wagon.

Making all allowances therefore, the total cost of the machine may be set down at say £4. 15s. per day ; which, divided by the output, gives as the cost of excavation say 1½d. per cubic yard for sand or gravel, and 2d. for hard clay.

Where the excavation is small, or the machine is under a disadvantage, these prices will of course be some what exceeded ; and 2d. to 3d. per cubic yard may be then allowed.