58 Professor W. A. Bone [Feb. 27, 



without flame in contact with the incandescent granular material. 

 The products of combustion having traversed the 4-foot length of 

 packed tube, pass outwards into a semicircular chamber at the back of 

 tlie boiler, and thence through a duct to the tubular feed-waste heater. 

 The fan which is attached just beyond this feed-water heater and is 

 driven by a three phase A.C. electric motor, sucks out the cooled pro- 

 ducts, at a temperature of 100° 0. (212° F.) or under, and discharges 

 them, through a short vertical duct, into the atmosphere. The 

 arrangement of the whole plant is shown in the accompanying dia- 

 gram (Fig. 13). 



The plant was successfully started up on November 7th, 1911, 

 for a month's trial run — day and night continuously — after which 

 it was opened up for an official inspection by the representative of a 

 Boiler Insurance Company. Everything worked without a hitch 

 during this trial ; steam was generated at 100 lbs. gauge pressure, 

 from a feed-water of about four degrees of hardness, whilst the 

 average temperature of the waste gases leaving the feed-water heater 

 was reduced to 80° C. (say 175° Fahr.), a sure indication of the high 

 thermal efficiency of the plant. When, at the conclusion of the 

 month's trial, the boiler was opened up for inspection, the combustion 

 tubes were found to be in good condition and free from scale : indeed, 

 owing to the extremely high rate of evaporation, the scaling troubles 

 experienced with other types of multi-tubular boilers appear to be 

 completely obviated, the scale being automatically and continuously 

 shed from the tube in thin films (about ^^ in. thick) as fast as it 

 is formed ; a very important advantage, as anyone who is plagued 

 by scaling troubles will appreciate. 



After this official inspection, the plant, having amply fulfilled our 

 guarantee, was taken over by the Skinningrove Iron Co., and it was 

 at once re-started under the direction of Mr. E. Bury, M.Sc, the 

 Manager of the Coke Oven Plant, who maintained it in continuous 

 commission for three months until the great coal-strike of 1912 

 brought everything to a standstill. 



At the end of July, 1912, after altogether five months actual 

 running, exhaustive trials were made under the personal superinten- 

 dence of an eminent American steam engineer who had crossed the 

 Atlantic with a commission to investigate the boiler ; he subsequently 

 reported the following results of a ten-hours' steam trial on July 29th, 

 which speak for themselves. 



Kesults of Steam Trial, July 29, 1912. 



Duration of test in hours 10 



Mean steam gas pressure, lbs. per sq. in. above 



atmospheric 97*2 



Total gas burnt, cub. ft. at N.T.P 101,853 



