14 



SCIENCE. 



[N. S. Vol. IV. No. 79. 



a dozen other heads to cover accessions in 

 the fields of general literature, more or less 

 of which is found in every technical col- 

 lection. The schedule is very complete and 

 was thought a most satisfactory one. 



Mr. Murray offered a paper on ' Structu- 

 ral Steel Fly Wheels.' The rapid increase 

 in the employment of ' high-speed ' engines, 

 especially in electric light and power sta- 

 tions, where great irregularity of load is 

 usual, has made the ' running away ' of en- 

 gines a comparatively frequent occurrence, 

 and accidents of great importance are not 

 unusual, involving loss of life and great de- 

 struction of property. The weakness of 

 the older type of fly wheel, due partly to the 

 fact that it is constructed of cast iron, partly 

 to its inefficient connection of parts, makes 

 it liable to go to pieces at a comparatively 

 low speed, and gives but small margin above 

 the ordinary working speed. Where, as is 

 probably not very uncommon, an engine, 

 when suddenly deprived of load, jumps up 

 to double speed before the governor can act, 

 or at a time, as is also not unusual, when 

 the governor is not acting, the old cast-iron 

 wheel is very sure to go to pieces and to 

 produce the effect of an exploding giant 

 bomb-shell. Various constructions of 

 wrought-iron and steel wheels have been 

 introduced, and Mr. Murray described a 

 steel wheel made of open-hearth structural 

 steel of about 60,000 pounds tenacity, and 

 built up of a series of discs forming the hub, 

 of a pair of dished disks constituting the 

 main portion of the wheel in place of the 

 ordinary arms, and a rim composed of 

 heavy steel boiler plate ; all rivetted to- 

 gether in such manner as to give a factor- 

 of-safety, as computed by the writer of the 

 paper, of twenty-six. All details are given 

 and the construction fully described. 



Prof. Goss exhibited the effect of long 

 connections upon the action of steam in 

 the steam-engine indicator and on the 

 diagram, as experimentally determined by 



him. He found that even short pipe con- 

 nections were likely to invalidate conclu- 

 sions drawn from the diagram regarding 

 the character of the expansion and com- 

 pression line or the quality of the steam. 

 For usual lengths of connection the area 

 of the diagram will be greater than that of 

 a true diagram, though that area may vary 

 in either direction from the proper dimen- 

 sions. To secure reliable results the in- 

 dicator must be attached to the steam 

 cylinder by very short and perfectly straight 

 pipes. 



Mr. Whitham described the recent ' me- 

 chanical stokers.' Of late years the supply 

 of fuel to the furnace of the steam-boiler 

 and the management of the fire has been 

 effected by the employment of these ma- 

 chines, which, very various in form, all 

 have the common function above described. 

 Their advantages, when successful, are their 

 adaptability to the cheap fuels ; their reduc- 

 tion, in large 'plants,' of the cost of labor, 

 by about forty per cent. ; their economy of 

 use of fuel, and the constancy or uniformity 

 of conditions of combustion which lies be- 

 hind the last-named advantage. They are, 

 however, costly, both in manufacture and 

 in repairs, are dependent upon the action of 

 a steam-engine and a steam-blast, and are 

 necessarily dependent, also, upon special 

 skill on the part of the attendants. Any- 

 thing going wrong, the whole establishment 

 may come to a standstill. 



Several forms of stoker are described and 

 their performance, as ascertained by trials, 

 tabulated. A number are found to be effi- 

 cient for special cases, each in its own 

 province. The engines use a fraction of 

 one per cent, of the steam made ; the fans 

 demand three to five per cent., and the 

 steam blasts from five to eleven per cent, in 

 the cases described. The 'stoker' is less 

 adaptable to a fluctuating demand for steam 

 than is hand-firing; but it is constant in 

 maintenance of a fire in good order, and 



