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found possible to drive this engine up to enormously high speeds, and to secure a smooth and safe motion. The piston-rod stuffingbox is placed at the end of the taper sleeve. This engine has been in operation for six months at the speed of 350 revolutions per minute, making millions of turns, without attention or visible wear. The valve was balanced and the speed was regulated by a throttling governor. The friction was low, as might have been anticipated from the lightness of the running parts.

The results obtained are shown in the following table. They are substantially the same as with the other engines, the speed variations showing increase of friction with velocity while the engine was underloaded; but it will be seen that the friction later became constant, and remained so, substantially, through a wide range of loading, up to the maximum reached. From 175 to 500 revolutions per minute, the friction increased according to the usual law; but, from 500 up to 600 revolutions, the internal friction remained sensibly constant, the loads being light throughout; while, when fully loaded, the speed ranging from about 175 to 912 revolutions per minute, the friction remained very nearly constant, and its variations were irregular. This is well shown by the diagrams which follow this paper.

TABLE III.

THE JARVIS ENGINE, 7" x 7".

Fiction with Change of Speed.

Steam Pressure Constant at 80 lbs. Engine Running Light. Trial No. 1.

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The earlier work already reported was mainly on a single class of engines, and it remained a question whether the variation of load in other forms of engine might not cause variation of the internal friction to an important extent, and according to fixed or various law, and, if so, what were the conditions producing such variations and what were those laws. Advantage was taken of the opportunity presented in this series of experiments upon the Lansing engines to determine what was the variation, if any, of the internal friction of the several classes there met with, in this respect. The variety there found was most favorable to this end.

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They were, as was seen, of various types, including the common. slide-valve with locomotive valve-gear; two with automatic valve motions, with balanced valves; one compound engine, condensing and with balanced valve; and the new high-speed engine of singular design which has been just described as the "Jarvis engine."

Table IV. gives the log of the straight-line engine tested by Professor Carpenter and Mr. Preston, and Table V. that of the 7 × 10 slide-valve, the working parts of the standard tractionengine of its builders. The trial of the latter was conducted with the "ahead motion" in gear, adjusting the link as required, to secure variation in the point of cut-off, setting it at 1,, and stroke for the several trials. The driving pulley was 42 inches in diameter, and its weight 320 pounds. The brake had an arm six

feet in length.

It was found impracticable to prevent some vibration while in operation; but the data may be relied upon as sensibly and satisfactorily correct. Fig. 25 exhibits the method of attachment. The average results were the following:

Friction of 7x 10 Slide- Valve Engine.

No. of Card.

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STRAIGHT LINE ENGINE, 6" × 12". FRICTION WITH CHANGE OF CUT-OFF

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36 2 35 3 34

4 34

5 33

6 32

8 38

9 39 10 39 11 39

12 44 13 46

14 44.5

15 44

16 42

2.83.00 2.80.511 3.0 3.25 2.76.517 1.03 253

004 1.08
3.25 2.94.551 1.07 253.004 1.12
2.75 2.65.479.94 244 .004.1.03 1.08
3.15 2.57.451 .95 237.004 1.06
.96 222.004 1.13
.89 222.004,1.06

2.8 2.95 2.85.519 3.0
2.2 2.50 2.64.464 2.9
2.6 2.70 2.89 .494 2.7
2.83.00 2.80.448 3.2 3.153.10.509
2.63.00 2.60.416 3.0 3.152.86.471

4.13.153.90.739 4.4 3.00 4.40.858 1.60 262.0061.62
3.83.15 3.62.694 4.1 3.00 4.10.808 1.50 263.006 1.511.42
3.83.15 3.62.687 3.4 3.00 3.40.665 1.36 266.0051.36
3.03.15 2.90.556 3.1 2.90 3.21.633 1.19 264.004 1.19

3.72.70 3.45.664 3.70 2.70 4.11.813 1.48 266.006 1.47
3.82.85 4.00.769 4.05 3.20 3.78.748 1.52 267 .006 1.51
3.72.85 3.89.743 4.30 3.204.05.795 1.54 267 .006 1.53 1.50
3.62.853.81.731 3.80 3.173.57.693 1.42 265.005 1.42
3.82.85 4.00.761 4.05 3.15 3.87.757 1.52 262

.006 1.54

17 39

18 39

19 40

20 41

21 41

4.12.80 4.38.818 4.403.154.17.800 1.62 264
4.62.85 4.83.901 4.903.174.65.893 1.79 259
3.52.85 3.69.705 3.85 3.173.63.713 1.42 265.005 1.421.58
4.4 2.85 4.62.882 4.00 3.15 3.81.748 1.63 265 .006 1.63
4.52.853.63.693 3.753.153.57.701 1.39 265 .005 1.39

.006 1 63

.007 1.83

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TABLE V.

TEST FOR FRICTION, WITH CHANGE OF LOAD AND OF POINT OF CUT-OFF.

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Cut-off.

Plotting the curve thus obtained, it is at once seen that the friction is decidedly increased with increase of load and decreased in the ratio of expansion. The first seven cards were calculated, assuming the head and back areas of piston equal, and thus obtaining the mean effective H. P.; while the other cards were worked up as indicated in the log. These results with changing cut-off were different from those secured by variation of load at constant ratio of expansion.

Placing a variable load on the brake arm, and thus varying the power from 0 to 21 H. P., the point of cut-off being retained constant, it was found that the friction was very nearly constant, and not variable with the load. The distribution of friction was then ascertained by a careful trial, the results of which are presented in another paper. There, as in the other trials described in these papers, the brake was handled substantially as described in papers already read before the Society.

The 8×12 automatic engine, which had been in use a year, and was thus well worked into smooth running order, was tested in the erecting room of the shops of the Lansing Co., bolted down on two blocks which were not heavy, but which answered their purpose fairly well. The log of the trial is given in full, and shows the internal friction to have been practically constant for all loads, and to have slightly increased with decrease of speed. The speed adjustments were made at the governor.

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