Proceedings, &c. t for 1884. 16$ 



June 25th, 1884. 



A paper was read giving a brief description of a visit to a coal 

 mine at Kilcunda. 



Mr. M'Lean then read a paper on " Some Remarkable Indicator 

 Diagrams." They were taken from the compound engine of the 

 dredge u Crocodile." 



This engine had been designed heavy enough to bring the 

 dredge out from England, and hence it was much too heavy for the 

 ordinary work of dredging. Again, it is subjected to very 

 varying resistances, according to the material cut out by the 

 buckets, so that the horse-power required from it may vary within 

 very wide limit. 



The most curious result was obtained with light load and boiler 

 pressure 50-lb., engines making 60 revolutions per minute. In 

 the high-pressure cylinder the maximum pressure was 24 lbs. ? 

 while the minimum was actually 3 lbs. below atmosphere. In the 

 low pressure the maximum pressure was 3 lbs., and the minimum 

 12 lbs., giving about one-quarter work of high-pressure cylinder. 



With higher boiler pressure, and the engine more heavily loaded, 

 the diagrams are of the normal form for compound engines. 



The " Crocodile" has two boilers, and the consumption of fuel with 

 one and two boilers at work deserves notice. 



Under ordinary conditions, Mr. M'Lean found it more economical 

 to use one boiler with a good fire than to use both even with a 

 very slow fire. 



But when the engines are heavily loaded, so that one boiler 

 would require to be forced, he found that the two with ordinary 

 fires gave better results. 



July 21th, 1884. 



Mr. Booth read a paper on "Speed Regulators." 



He divides speed regulators into three classes: — (1) Those 

 which use up none of the driving power, but simply store energy, 

 as the fly-wheel. (2) Using a small fraction of the driving power 

 in regulating the speed of the engine, such as ordinary governors. 

 (3) Those in which regular speed is essential, and to attain which 

 we can use up all the driving power; such are astronomical pendu- 

 lums of various kinds. 



The incandescent light is, perhaps, the most delicate test of 

 speed which we commonly meet ; eight per cent, variation in speed 

 makes all the difference between full on and quite out. 



The chief causes of inaccuracy in governors of the second class, 

 and the methods to be used in order to overcome them, would 

 seem to be — 



