1819."] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



169 



Safety valves. — Turning joints in pipes. — The diiferent centres 

 (fig. 6, A) and journals in turning-lathes. — Spindles. — Axles of 

 railway turn-tables. — Footsteps for upright shafts. — Couplings for 

 shafts." — Collars of screws (fig. 3, B, a and b) — Glass stoppers; — in 

 short, all those contrivances which present similar rubbing sur- 

 faces. 



8GLNP 

 The friction is a mniimum and equal to „ /r)j_ j;-, i ^^here 



P = the whole pressure which the rubbing surfaces have to bear 



in the direction of their axis. 

 D = the diameter of the larger part. 

 d = the diameter of the smaller part. 

 L = the length of the generating curve. 



G := distance of the point of gravity of the curve from the axis. 

 C := co-efficient of friction. And, 

 N ^ number of revolutions. 



Measures to be taken of equal units. 



William Fairbairn, Esq. having kindly assisted me in bringing 

 out my scheme, I have great pleasure in publicly acknowledging 

 my obligations to him. This gentleman gave me his favourable 

 opinion about the principle described above, and allowed me to 

 make some trials on one of his locomotive engines. 



I beg to offer my services as patentee, and as manufacturer of 

 most of the articles mentioned above, as well as of instruments 

 for drawing the curves. 



Christian Schiele, Mechanician. 



Manchester, May, 1849. 



STEAM AND VACUUM GAUGE. 



{From the Journal of the Franklin Institute.) 



The Committee on Science and the Aits, constituted by the Franklin Insti- 

 tute of the State of Pennsylvania, for the Promotion of the Mechanic 

 Arts, to whom was referred for examination and report, an "Engine j 

 Register and Manometer Steam and Vacuum Gauge," invented by Mr. 

 Paul Stillman, of the City of New York, Report: — 

 That the instrument referred to is designed for application to 

 marine steam-engines, and that it is, in outward appearance, simi- 

 lar to the marginal sketch. 



It is threefold in its purposes — consisting, 1st, of a circular 

 cast-iron box, faced with a dial, in which are cut side by side, six 

 (or more as may be required) slots, through which may be seen 

 the numbers representing the revolutions of the engine; this is 

 denominated the "counter" or "register;" 2nd and 3rd, of two 

 gauges, one for steam, the other for vacuum, connected by suit- 

 able pipes with the boiler and condenser. Both these latter 

 consist of vertical glass tubes, hermetically sealed at their upper 

 ends and having their lower ends immersed in small chambers (the 

 joints being insured perfect by tinning the brass glands surround- 

 ing the tubes.) These chambers communicate with the reservoirs 

 for the mercury only by the lower end of the small chamber, into 

 which is screwed a plug; so that it is only by the minute leakage 

 around this screw, that the same pressure is maintained on the 

 mercury in the tube and that in the reservoir. The object of this 

 arrangement is to prevent the too rapid agitation of mercury con- 

 sequent on differences of pressure, and also to enable the tubes to 

 be filled and then inverted in their reservoir, without loss to the 

 contents, — in fact, supplying the place of the bulb in common 

 gauges. 



The steam gauge then, having been partially filled, indicates by 

 the compression of air, caused by the forced ascent of the mer- 

 cury; and the vacuum gauge, being at first entirely filled, indicates 

 by the descent of the mercury, as in common gauges. To pre- 

 vent, in the steam gauge, the soiling of the tube, caused by the 

 oxidation of the mercury, a small quantity of naphtha is intro- 

 duced on its surface. These gauges are thus presented in a com- 

 pact form, and in a manner not very liable to derangement. But 

 as it would require a practical experience to test their supposed 

 advantages over those in common use, the committee, at present, 

 will confine themselves to a consideration of the "Register," of 

 which the following is a description. 



By an attachment to any suitable part of the engine, a vibratory 

 motion is communicated to an arm attached to a central horizontal 

 shaft, placed parallel to the dial, and within the cast-iron box — to 

 the ends of which is also fixed a frame carrying a small shaft 

 parallel to the former, on which six palls or arms are attached, 

 side by side, and at a certain distance apart, in such a way that 

 the right hand pall may fall without the others, but cannot rise 

 without carrying the rest. 



This frame-work, with the pall-shaft, &c., is made, by the motion 

 of the arm attached to the engine, to describe an arc of 36°, or to 

 move through one-tenth of a circle. 



The ends of the palls respectively rest on, and slide over, six 

 cylinders placed side by side on the central shaft, all of which are 

 free to move in the same direction and independently of each 

 other, and are arranged in the following manner: — 



For the sake of clearness, we shall number them 1, 2, 3, 4, &C., 

 beginning with the right-hand one. 



On the right-hand edge of each cylinder are cut 10 slots, and on 

 the left-hand, which overlaps the edge of the next, only one slot; 

 these slots being of such a size as will admit the end of one of the 

 palls; then on the back motion of the frame-work, &c., the pall is 

 carried back till it drops in, when the forward motion carries with 

 it the cylinder so locked. 



In the central spaces (between the laps) in each cylinder, and 

 opposite to one of the slots in the dial face, the numbers 1, 2, 3, 

 &c., to 0, are engraved at equal distances round the circumference. 



The palls are placed one over each of the slots, so that the pall 

 can fall into the inner cylinder only when the slot in the outer 

 one comes directly under it; and as this occurs only once in a 

 whole revolution, and as the motion of the palls is only through 

 one-tenth of a circle, it follows that cylinder No. 2 can only be 

 moved through one-tenth of its circumference, after cylinder No. 



1 has moved a whole revolution, or ten times that space, and so 

 on. Thus, if the figures on No. 1 represent units, those on No. 



2 will be tens, on No. 3, hundreds, tkc. ; and extending the same 

 principle. No. 1 must move round one hundred thousand times to 

 produce one revolution of No. 6. It will be observed that every 

 revolution of the engine must insure one-tenth of cylinder No. 1 

 to move round, inasmuch as the ten slots in its right-hand edge are 

 not covered by any other cylinder, as is the case with the rest. 



The cylinders being free to move in the direction of their 

 motion, or forward, they may be adjusted at any time to their 

 starting point, without deranging any of the palls, or even open- 

 ing the case. 



The committee judge the following to be the advantages of this 

 arrangement: — 



1. The compactness and symmetry. 



2. The ease veith which the result may be read. And, 



3. The facility of adjustment. 



The two latter being important considerations in an apparatus of 

 this kind. 



The arrangement is also probably of less expense than the old 

 form of counter. 



In view of all which points, the committee are of opinion that 

 Mr. Stillman is entitled to the First Premium awarded at the Ex- 

 hibition, where it was placed by him in October last. 



By order of the Committee. 



Philadelphia, February 9, 1849. 



William Hajiilton, Actuary, 



23 



