284 Mr Russell on a Marine Salinometer, Sfc. 



so made, as shewn in the drawing, that by their means each of 

 the tubes inside of the boiler may be shut off from the glass 

 tubes, and also may be connected with the tube H, leading 

 from the feed-pipe of the boiler ; I, a cock affording the means 

 of shutting off the tube E from the glass tubes, and also of 

 connecting either of these glass tubes with the tube K, lead- 

 ing to the bilge of the vessel ; each of these cocks has a handle, 

 and when the instrument is indicating, the three handles hang 

 perpendicularly downwards. Tobringthe instrument into ope- 

 ration, the three handles must first be put in the position " • 



which has the effect of allowing the brine to flow right up the 

 glass tube A, and out through the tube K, into the bilge of 

 the vessel ; this having been done for so long a time as that 

 A and its tube inside the boiler be thoroughly cleansed and 

 filled with brine, the handles are then to be put in the posi- 

 tion • • , which, in like manner, cleanses and fills B and its 



tube inside of the boiler with brine ; finally, bring the handle 

 of the top-cock into its original position, and put either of the 

 lower handles horizontal, which forming a connection of the 

 feed-pipe with one of the tubes inside of the boiler fills that 

 tube with feed- water ; thus there are in the two tubes inside of 

 the boiler two columns of water of different specific gravities, 

 the one being brine, the specific gravity of which is to be 

 measured, and the other feed-water, the specific gravity of 

 which is pretty nearly constant, so long as the temperature of 

 condensation is the same, and does not vary much let the tem- 

 perature of condensation be what it may ; but, inasmuch as 

 these columns of water are of different specific gravities, the 

 pressure on the bottoms of them will force the lighter up the 

 glass tube, until such a quantity of brine has followed it as 

 makes it of equal weight with the other ; and hence, in the 

 two glass tubes, the water stands at different heights, the mag- 

 nitude of which difterence becomes known by means of the 

 scale fixed betwixt the glass tubes, and therefore also the de- 

 gree of saturation of the brine. 



The use of this instrument, which might be called a Sali- 

 nometer, is not confined to this one object, for it answers 



