15 



slightest over the equilibrium, the weight H runs along the 

 bar G., and shuts or opens the tap instantly. 



This arrangement has now been in work some months, and 

 gives every satisfaction. It is allowed to work day and night, 

 and has always started or stopped the motor at the proper time. 



No. VI. 



ON AN IMPROVED PUMP FOR SALT WATER. 

 Figure 2. 



Three or four years ago when my aquarium was built, I 

 had one of Leete, Edwards and Norman's rotary vulcanite 

 pumps supplied, along with all the piping to fit up the tanks. 

 It has been working intermittently day and night ever since, 

 so that it has been fairly tested. Some months ago I made 

 up my mind to give it up, and use a double-action lift-and- 

 drive dump in its stead, for the following reasons : — 



1. I was given to understand I should require less power 

 to lift the same quantity of water. 



2. Whenever the water motor was working below a 

 certain speed, there was not enough force to lift the salt 

 water into the tower tank, and thus the motor was working 

 without the pump doing its work. By the new arrangement 

 the shaft of the water motor is connected directly with the 

 piston of the pump, so that if the motor moves ever so 

 slowly the pump must move with it. 



3. Sometimes the cups of the rotary pump would catch 

 together, and stop all the apparatus until we could get a 

 mechanic to take the pump to pieces. 



By our new arrangement these difficulties are avoided ; we 

 get more regular pumping, and an economy in cost of turning. 



The working plans were made for me by my friend, Mr. J. 

 T. Nelson, of Leeds, and the work was mostly carried out in 

 our workshop. The general construction will be understood 

 by a glance at the sketch. A. is a bored glass cylinder, 

 obtained from Messrs. Chedgey. The piston rod is of iron 

 covered with vulcanite ; while the piston itself is made of 

 lignum vitce, with a round india rubber ring in the centre to 

 form perfect contact. The ends B. and C. are also of lignum 

 vita, and the round ball valves are of india rubber weighted 

 in the centre with lead. The whole is bolted to a plank D., 

 and connected with the shaft of the water motor in the 

 ordinary manner. The pipes E. E. are of iron lined with 

 glass, and supplied by Messrs. Chedgey. It will be easily 

 seen from the sketch that a stroke in either direction both 

 fills the cylinder from below, and drives the water already 

 in the cylinder into the tower tank. 



H udder sjield, 



February 28M, 1884. 



