Leal 
re 
280 WILLIAM FIELD HOW. 
Many manufacturers of rough girder work make a wooden tem- 
plate of doubtful accuracy, through which they make a circular 
white mark upon the plate or bar to be punched, and the material 
So marked is guided by a workman under the flat ended punch, 
and it depends upon the experience of the workman in adjusting 
the plate, if the punch makes the hole in the place required, or not. 
In such works no time is lost after punching one hole in throwing 
the punch out of gear and adjusting the plate for the next hole. 
The plate is simply moved forward, and if it is not in the right 
position when the punch comes down, the hole is made in an 
incorrect place. 
In steel plates all holes should be drilled, but if the steel be of 
a mild character, such as is used for constructional work, they may 
be accurately marked off, punched small in the manner recom- 
mended for iron plates, and then drilled out to the required finished 
sizes, the largest diameter of the punched holes being three-six- 
teenths of an inch less than the finished sizes. In steel of a harder 
character, such as is used for permanent way rails, drilling out of 
the solid should invariably be adopted. 
To roughly ascertain the effect of punching some of the New 
South Wales Government seventy-one and a-half pounds steel rails, 
the author had pieces, each six feet long, cut from the same rail. 
One of these pieces was tested as cut from the rail; the second 
piece had a one and one-eighth inch hole drilled through the centre 
of the web in a similar position to that occupied by a fishing hole ; 
and the third specimen had a hole of the same size and in a similar 
position punched through it. When these pieces were placed upon 
bearings three feet six inches apart, with the holes adjusted directly 
under the drop, the first and second pieces, being without hole 
and with hole drilled, respectively, withstood three blows from a 
ton weight falling six feet, followed by two twelve feet blows from | 
the same weight, and the deflections in each case were practically q 
the same; whereas, the punched specimen broke under the first 
blow and after the ton weight had fallen upon it from a height of 
only two feet. This experiment, which was carried out upon 
