AMERICAN ~IECHANICS' blAGAg|NE,° ~

A D D F.,N D ,~..

din approximation to an estimate of the cost of a re_all-way (lock, at Philadelphia, for ships of 500 tons, and under.

The Implements (expedient to be preserved) viz: the diving bell~ pile driver and their scow~ costa t New York~ - - - $3~800

Various tools, . . . . . . . . -. 700 The Foundation Piles, the number and length of them will

depend on the nature of the ground. Assuming that the number will be S00, and the materials and fixing at ~3 each, is - - 900

Frames to bear the iron rails, and connect all together 7~600 at 50 cents, . . . . . . . . 2~280

The Capst,~n House, two stories high, . . . . 600 h'on Work, consisting of lhe rails, ~'ack, saddle-pieces, axles,

wheels, gear of the windlass, shafts, plummer boxes, levers, bolts aml fastenings of every kind, according to ex- perience in New York, - . . . . 12,500

The Chain is of a peculiar construction, 300 feet will weigh c20~400 I1)s. at ~0 cents, - - 4,000

Lab,ur , driving the Iilles,. ,and carpenters ~ work~ estimated at 3,500 Land, and Wharves, will probably cost about - - - 10,000 Sul~ervision, - - - 1,000

~58,780

I f the same establishment should have a second rail-way, of dimensions suitable for ships of £00 tons and under~ it may be built for the additional sum of - - ' ~17,000

The Income from the principal Dock, besides the wharfage, may be estimated as follows; ~he rates of toll being placed at 25 cents a ton, as established in New York. I f then one hundred vessels~ averaging ~00 tons, be drawn up in a year, it will amount to 5000 dollars. "]'he expense of management inust be deducted~ but a rea- sonable income fi'om the investment will still remain, rl~e Dock would, however, be capable ~)f doing more business, should the de. mand for its use be gl:eater.

Zist of inventions belonging to Thomas~s rail-way dock. Blocks and wedges for gaining access to the bottom of the keel,

patented May 17th, 1822. System of shoring~ patented February ~4th, 1826. Foundation Instruments, and Bilge Levers, patented November 6th~ 18o(3. Authenticated specifications of the shear shore screw, and of the reversed movement~ entered August 12tl b 18~6. An improvement in the rail way dock brake, May 7th, 18~26; and in the lit'ring blocks, May 16lib 18~26; for which pa'tents are in~ tended to be taken out, at maturity.