An Improved Grab Crane. 1G9 



The grab bucket can be opened in three ways — (1) By 

 pulling the lowering chain while holding the lifting chains, 

 which raises as well as opens the bucket ; (2) By holding 

 the lowering chain and letting out the lifting chains, which 

 lowers as well as opens the bucket ; (3) By a combination of 

 the first two methods, which simply open the bucket without 

 altering its height. These methods of opening the bucket 

 have been found to be of great advantage, for the driver 

 need not be very particular as to the height of the grab 

 bucket when about to open it, as he has complete control of 

 all its actions. 



The cheeks of the crane are formed of wrought iron, and 

 with a roof serve as a protection from the weather. 



The Melbourne Harbour Trust Commissioners having had 

 a crane on this principle constructed, mounted on a Smeaton's 

 ring and built on a special pontoon for dredging purposes, 

 I have been enabled to prove by actual experiment that the 

 dynamical principles of the machine, as described, are correct. 

 The crane is now at work on the Yarra, where it is found 

 to be capable of making a complete set of dredging opera- 

 tions in forty-five seconds, so that the bucket, containing 

 from two and a-half to three tons of silt, can be lifted easily 

 within one minute, controlled by one man. 



The crane is capable of being constructed in a portable 

 form. The modification referred to in the patent specification 

 is designed for digging dams and other pastoral station work, 

 and for portability. 



Art. XIV. — A Note on the Apparatus to be used in 

 Viewing the forthcoming Transit of Venus, in 

 December, 1882. 



By R. L. J. Ellery. 



[Read 14th September, 1882.] 



