178 REPORT—1850. 
November 8th: 
Weights laid on Deflection at the point 
in tons. of the jib in inches. 
2 "32 
3 “50 With 5 tons suspend- 
4 ‘65 | ed the crane was turned 
5 *90< completely round, with- 
6 1°05 | out any alteration in the 
7 1°20 | deflection. 
8 1°35 
9 1°50 
10 1°70 
With this weight the crane was again turned round; the deflection in 8 minutes 
increased to 1°85 inch, when it became permanent, after sustaining the load during 
the whole of the night, a period of about 16 hours. 
On November 9th the experiments were resumed as follows :— 
11 2°05 
12 2°22 
13 2°40 
14 2°60 * 
15 2°80 
16 3°00 
17 3°20 
18 3°50 
19 3°73 
20 3°97 
On again turning the crane round with a load of 20 tons, there was no perceptible 
alteration in the deflection, and the permanent set after removing the load was °64 
inch. 
From the above experiments, it appears that the ultimate strength of the crane is 
much greater than is requisite in either theory or practice ; and although tested with 
nearly double its intended load, this was still far short of its ultimate power of resist- 
ance, which by calculation is five times greater than its nominal power. 
The advantages peculiar to this construction of crane, are its great security, and 
the facility with which bulky and heavy bodies can be raised to the very top of the 
jib without the least risk of failure. It moreover exhibits, when heavily loaded, the 
same restorative principle of elasticity so strikingly exemplified in the wrought iron 
tubular girders. These constructions, although different in form, are nevertheless the 
same in principle, and undoubtedly follow the same law as regards elasticity and 
their powers of resistance to fracture. 
Reference to the figures. 
Fig. 1 is a side view of the crane with a portion of the side removed from A to the 
foot, in order to show.the cast iron cylinders built in the masonry, the rollers which 
encircle the body of the crane and support the stem vertically, with its rollers and 
_bearings acting against the interior recess of the large circular plate a. Between 
the plate and the frame attached to the crane is a double ring which contains the 
rollers, giving a rotatory motion to the crane in any direction. Immediately above 
the rollers is a platform, 12 feet in diameter, attached to the stem, on which the men 
stand to work the crane. This platform also enables a man, by turning a handle at 
b, to move the crane round in any direction at pleasure. 
Fig. 2 is a ground plan of the crane and platform, showing the upper flange of 
the large ring with the holding down bolts at ὁ, 6, c, &c. ᾿ 
Fig. 3 is a section of the body of the crane taken above the Quay Wall at the 
point A. The cells are carried along the concave side of the jib when they terminate 
in two cells near the top, and also in two cells near to the bottom, where the stem 
enters the cast-iron shoe already mentioned. 
