should be especially useful in this respect.  The question has indeed attracted the attention of more than one manufacturer, and reference is made to a particular type of small rotary motors which are being constructed by MM.  Riedinger & Co., and which is stated have given very excellent results.  These engines were specially used for working sewing machines and developed on the brake an efficiency of 34.07 and 51.63 foot pounds per second.  Trials were made with a half horse power variable expansion Riedinger engine.

TRIALS OF A SMALL ROTARY RIEDINGER ENGINE.
____________________________________________________________

__
|       |
Number of trials.                            |   I.  |   II.
______________________________________________|_______|_____

__
|       |
Initial air pressure.     lb. per square inch |    86 | 71.8
"      temperature.           deg.  Cent. |   +12 |  +170
Ft. pounds per second  measured on the brake. | 51.63 | 34.07
Revolutions per minute.                       |   384 |  300
Consumption of air for one horse power per    |       |
hour.                                      | 1,377 |  988
______________________________________________|_______|_____

__

TRIALS OF A 0.5 HORSE POWER RIEDINGER ROTARY ENGINE.
____________________________________________________________

_________
|      |      |      |
Number of trials.                        |  I.  |  II. | III. |  IV.
__________________________________________|______|______|___

___|_____
|      |      |      |
Initial pressure of air.  lb. per sq. in. |   54 | 69.7 |   85 | 71.8
"  temperature of air.    deg.  Cent. |  170 |  180 |  198 |    8
Final        "        "            "      |   25 |   20 |  ... |   25
Revolutions per minute.                   |  335 |  350 |  310 |  243
Foot pounds per second measured on        |      |      |      |
brake.                                 |  271 |  477 |  376 |  316
Consumption of air per horse power        |      |      |      |
and per hour.                          |  883 |  791 |  900 |1,148
__________________________________________|______|______|___

___|______

TRIAL OF AN 80 HORSE POWER (NOMINAL) FARCOT STEAM ENGINE.
____________________________________________________________

_______
| R p  |      |                  |
| e e  | I    |                  | Consumption of
| v r  | n    |   Temperature    |  air per horse
| o    | d h p|      of air.     |  power and per
| l m  | i o o|                  |      hour.
| u i  | c r w|__________________|________________
| t n  | a s e|         |        |       |
Motor.        | i u  | t e r|Admission|Exhaust.|Nominal| Brake
| o t  | e   .|         |        | horse | horse
| n e  | d    |         |        | power.| power.
_________________|_s_.__|______|_________|________|_______|_

_______
|      |      |  deg.  C | deg.  C |       |
Nominal 80 horse | 54.3 | 72.3 |    129  |   21   |  469  |  517
power single     | 54.3 | 72.3 |    152  |   29   |  437  |  475