TRANSACTIONS OP THE SECTIONS. 163 



any part, as the crown of the arch, in cylindrical boilers, collapse, an 

 accident becomes probable. 



On a Substitute for the Forcing-Pump in supplying Steam-Boilers, 



4c. By Mr. Maule. 



This was a hollow cock having an orifice, which being uppermost, 

 the plug became filled with the liquid, and then, being turned half 

 round by the motion of the piston, the liquid could run into the vessel 

 below. 



Notices on the Resistance of Water. By John Scott Russell, 

 F.R.S.E. 



The author, in conjunction with Sir John Robison, being still en- 

 gaged in researches bearing on this subject, it is deemed unnecessary 

 to anticipate by partial notices the full Report which is expected from 

 these gentlemen. 



On Methods of Filtering Water. By J. T. Hawkins. 



In this paper the author detailed the various essentials for a durable 

 and simple filter for obtaining pure water. The charcoal must be per- 

 fectly well burnt, and kept from exposure to the atmosphere. A test of 

 good charcoal is, that when pulverized, it sinks rapidly in water. The 

 charcoal must be supported on an indestructible material, as a plate of 

 burnt clay perforated with holes. The filter may consist of a common 

 garden-pot, or similar vessel, with holes at the bottom : the lower part 

 may be filled with round pebbles, then some smaller pebbles, then some 

 coarse sand, and finally a stratum of pounded charcoal, of about three 

 or four inches in thickness. It is a great mistake to put any material, 

 as sand, above the charcoal, with the view of arresting the grosser par- 

 ticles of impurity, as the sand will quickly stop up, and be impervious 

 to water. A filter thus prepared will render water perfectly clear and 

 sweet for many years. 



On a Method of making Bricks of any required Colour. 

 By Mr. DoBSON. 



On Coal-Mine Ventilation. By Mr, Fourness. 



Models were exhibited and partially explained of a suspension bridge 



of wire, erected over the river Avon, near Bath, by Mr. Dredge. 



A method of Pumping Water from Leaky Vessels at Sea, by Mr. Dal- 

 ziell. The machine is worked with a piston, the motion of the vessel 



M 2 



