February 21st, 1922.] Proceedings. xvii» 



Ordinary Meeting, February 21st, 1922. 

 Mr. T. A. Coward, M.Sc, F.Z.S., F.E-S. {President), in the 



Chair. 

 A vote of thanks was passed to the donors of the books upon 

 the table. These included Vol. 53 (1921) of the Transactions and 

 Proceedings of the New Zealand Institute, presented by Mr. 

 Edward Melland ; and Power, October, 192 1—, presented by Mr. 

 C. E. Stromeyer. 

 Mr. William Thomson, F.R.S.E., F.I.C, read papers entitled : 



I. "Estimation of the Smoke in the Atmosphere of 

 Manchester, and Apparatus Used Therefor.'* 



The author found, by experimenting in the year 1913, that 

 if a known volume of air were filtered through white filter or 

 blotting paper, the smoke suspended in the atmosphere in an 

 almost colloidal condition could be removed from it and remain 

 fixed on the surface of the paper amongst the interstices of its 

 fibres, leaving a stain more or less dark or jet black, according 

 to the condition of the atmosphere at the time. 



To study the conditions of the atmosphere as regards smoke 

 at different times of the day and night he constructed a machine 

 in a primitive form which answered the purpose; but as 

 mechanical improvements suggested themselves new machines. 

 were made, till finally Mr. W. Gibson Rapp, of Birmingham, 

 after two or three years of experiment, constructed one on more 

 accurate mechanical lines. This was altered to a large extent 

 by the author, and from the results of their combined experi- 

 ences the fifth and final re-construction of the machine was made 

 by Mr. Rapp. This now acts perfectly, and may be run night 

 and day without stopping, furnishing records of the smoke 

 every 15 minutes. It consists of three pumps submerged in 

 mineral oil in a cylindrical vessel worked by a spindle which 

 passes through a small electro-motor, the one end actuating 

 the pumps and the other having attached to it a fan working^ 

 in a 3-inch galvanised iron tube which brings the air from the 

 outside and passes it in a continuous stream over the small box 

 connected with the pumps, on the top of which is a hole 

 Jin.Xiin., over which a ribbon of filter paper is passed and 

 through which the air is sucked. Every 15 minutes the paper 

 is drawn forwards half an inch by the action of the soft iron 

 core of a solenoid magnet which is drawn into the coil when the 

 current is switched on by a contact in the clockwork. This 

 current simultaneously performs five different operations— (i) it 

 lifts for one-sixteenth of an inch a weight of 10 lbs., which 

 presses on the paper around the hole for the 15 minutes, during- 



