The Country Gentleman s Magazine 



272 



by copper pipes, through which a portion of 

 the exhaust steam is made to pass. 



The boiler — which, aided by good stoking, 

 shewed such exceptional evaporative power 

 during the trials — is distinguished rather by 

 general excellence in the proportions than by 

 any peculiar features. It is, however, pro- 

 vided with a steam dome, a valuable adjunct 

 for insuring a supply of dry steam, and the 

 fire-box is made with the portion below the 

 fire-door completely cut away, the opening 

 being filled in with a block of fire-clay at- 

 tached to a suitable casting. This mode of 

 constructing the fire-box has been adopted by 

 Messrs Clayton & Shuttleworth for many 

 of their engines for some time past, and we 

 consider it to be one worthy of being still 

 more extensively adopted. Amongst other 

 advantages it does away with a part of the 

 fire-box, which frequently gives trouble, while 

 by removing the block of fire-clay very ready 

 access is obtained to the interior of the fire- 

 box. 



The engine we have been describing was 

 submitted to two trials at Cardiff, and on the 

 first occasion it run 4 hours 51.3 min., and 

 on the second 5 hours 1.06 min. mechanical 

 time, with an allowance of 14 lb. of coal per 

 dynametrical horse power; these performances 

 corresponding to a consumption of 2.88 lb. 

 and 2.79 lb. of coal respectively per dyname- 

 trical horse power per hour. During the first 

 trial the boiler evaporated 11.39 lb., and 

 during the second run 11.32 lb. of water per 

 pound of coal ; these rates of evaporation 

 being by far the highest of which we have 

 ever heard as being attained by a portable 

 engine boiler. The whole performance of the 

 engine was in fact admirable, and reflected 

 the greatest credit on all concerned in its 

 construction. Of the general design of the 

 engine we need only say that it was distin- 

 guished by that excellence in the proportions 

 and general gracefulness of outline which 

 characterise all the details of Messrs Clayton 

 & Shuttleworth's engines, while the work- 

 manship was simply perfect. In our Tables 

 published at the time of the Cardiff trials we 

 gave the dimensions of Messrs Clayton & 

 Shuttleworth's engine with the rest ; but for 



convenience of reference we repeat them 

 here, and we also append an abstract of the 

 results obtained during the second and 

 concluding trial. 



ft. in. 



Diameter of cylinder o 9 



Stroke i o 



Length of fire-box inside 2 2 3-S 



Width ,, „ 2 5 



Height ,, ,, above firebars 2 6'^ 



Number of tubes ... ... 5^ 



Length ,, 60 



Diameter of tubes outside o 23-16 



Area of firegrate as u.sed on trial .. 3. 13 sq.ft. 

 Aggregate area of spaces between 



firebars as used on trial ... ... 1. 19 sq.ft. 



Heating surface : Tubes (outside) 192. sq. ft. 



,, ,, Fire-box 25.12 sq. ft. 



Total.. 



227.12 



Diameter of blast nozzle o 2% 



Nominal speed in revolutions per 



minute no rev. 



Mean speed in revolutions per minute 



during trial 112.64 ,, 



Mean piston speed in feet per minute 225.58 ft. 



Load on brake 14 HP. 



Actual time run with allowance of 

 14 lb. of coal per dynametrical 

 horsepower 4h. 54m. . 



Mechanical time = total number of 



revolutions -f nominal speed ... 5 h. I "06 m. 



Consumption of coal per dyname- 

 trical horse power per hour ... 2. 79 lb. 



Consumption of water per dyname- 

 trical horse power per hour ... 31.71 ,, 



Water evaporated per pound of coal 11.32 , , 



Coal consumed per square foot of 



firegrate per hour ... ... ... 12.48,, 



Temperature of gases in smoke- 

 box 39o°to4i5''Fahr. 



Temperature of feed 210" 



It should be borne in mind that the quan- 

 tities of water given above as being consumed 

 per dynametrical horse power per hour, and 

 as being evaporated per pound of coal, do 

 not include the water arising from the con- 

 densation of the steam, in the jacket, which 

 water was, of course, continually draining 

 down into the boiler and being re-evaporated 

 without its being possible to take an account 

 of it. The evaporative power of the boiler 

 was, therefore, really higher than would 

 appear from the above figures. 



