590 
Mr. W. S. Ward, the Secretary, read the first 
paper : — 
ON AN IMPROVEMENT IN PRESSURE GAUGES. BY W. H. 
BARTHOLOMEW, ESQ., C.E., RESIDENT ENGINEER, AIRE 
AND CALDER NAVIGATION. 
The writer's attention has for some time been directed 
to devising some means of increasing the employer's control 
over his engine driver, and it has led him to the improvement 
which he hereafter proposes to describe. 
In laying this subject before you, it may be desirable here 
to state that he conceives it, and proposes to treat it, as more 
particularly applying to the employment of high pressure 
steam, and to engines of this class, perhaps, more especially 
the locomotive and steam boats, he selects as examples, be- 
cause they are, when at work, so little under the eye of the 
employer. 
It is a well known fact amongst individuals conversant 
with the working of the class of engine mentioned, that it is 
too frequent a practice (and perhaps a great temptation if 
not controlled,) for engine drivers — in the locomotive for 
instance, when behind time, or when ascending heavy 
gradients over loaded ; and, in the case of steam boats, when 
contending against head winds, or running in competition 
with other boats — to screw down the safety valves much 
beyond the limited pressure, thereby in all probability 
endangering the boiler under his charge, or to say the least, 
injuring it in a greater or lesser degree, without leaving any 
immediate trace behind to convict him of his recklessness. 
To obviate this, the writer proposed to the Patentee of a very 
recent Pressure Gauge to add to the ordinary working 
index or pointer of the dial another index, which, for better 
comprehension, may be termed a Station Register Index ; 
this Index, which is placed entirely out of the control of the 
