ON MANGANESE BRONZE. 387 
PERMANENT DEFLECTION IN INCHES, IN THE LENGTH OF 12 INCHES. 
poe Weowart Guy-MErAL MANGANESE BRONZE 
Cie gy) ee eel 
Blows] Stafford- : No. 3 
SiralRolled Cast in Sand Cast in Sana || N°- 1 Forged 
No.1} No. 2} No.1] No. 2| No.3} No.4] No.5} No.6] No. 3] No. 4 || No. 5| No.6 
1 | -57|.-58 82.1 -86 | 990 | °:72 | °73 “46 ‘66 ‘60 ‘59 ‘60 
2 {1°10} 1:15 |1°50 | 1°58 |1°63 |1°32 | 1:42 | and 1:20 | 1:15 1:06 | 1:08 
8 |1°62] 1:71 | 1:70 | 2-22 | 2-35 | 1:92 |1:52 |broke} 1:70 | 1:60 1:44 | 1:50 
4 |2-13} 2-23 | and | and | 2°86 |1-94 | and | — 2:23 | 2:07 || 1:80] 1-89 
5 |2-65| 2-77 |broke|broke} and | and /brake| — 2-67 | 2:52 || 2-12 | 2-26 
6, | 3'19),.3:37.| — | .—..|broke|broke|.— | — 3:11 | 2:97 || 2:45 | 2-65 
Aa ocoo | — | | 3:58 | 3:39 || 2:77 | 2-99 
23) CEB eR el) ira | jp rer aere 4:02 | 4:04 || 3:05 | 3-38 
9 | not/broken}| — Sf} — |] ape not | and 3:33 | not 
10 = = — — | — .| — | broken} broke || not {broken 
11 — — }/— +} —} — | — — half ||broken} — 
12 — — — — — — — thro: = — 
13 a i | | esa | et ge = i = 42 
Nest Gearing. 
By Professor H. C. FLEEMInG JENKIN, F.R.S., M.Inst.0.E. 
[A communication ordered by the General Committee to be printed in extenso 
among the Reports. | 
[PLATES XIII, XIV., and XV.] 
Ty the winter of 1882, when engaged with Professors Ayrton and 
Perry in the development of designs for telpherage, I was shown by them 
the design for driving a dynamo by two rollers, shown in fig. F. 
This plan has been used, I believe, in connection with blowers for some 
time, but I am not aware with what results. It has the merit of re- 
leving the bearing of the dynamo from unnecessary pressure. It seemed 
to me that perhaps better results might follow if a belt were allowed to 
embrace the three pulleys, as in fig. 2, a plan which I have since learnt 
is adopted by Mr. Killingworth Hedges. I was, however, by no means 
convinced that a short tight belt in these circumstances would work 
) well, and I was thus led to consider the possibility of including the set of 
| pulleys inside a rigid ring. The only difficulty appeared to be how the 
pressure should be maintained. The idea of a rigid smooth ring enclosing 
a set of smooth rollers, so pressed by the ring and against each other as 
to bring no pressure on the spindles or shafts, was not novel, although I 
was at first not aware of this. Mechwart has used the principle in his 
rolling mills, although in this case he does not use the rollers as gear, 
but drives the shafts by spur-wheels. Mr. Foster, however, in 1882, 
took outa provisional specification in which one form of nest gear is 
clearly described. Fig. 3 shows a model of this gear, which has been used 
cc2 
