FIELD ARTILLERY FIRE. 
203 
CHAPTER IV. 
Ranging . 1 
The object of the process of ranging is to find out ) irrespective of the distance 
in yards , what elevation must be given to the guns in order that the mean trajectory 
of the battery may pass through the centre of the target, i.e. the relative range , 
and to determine the correct length of fuze . 
Here be it noted that, tbe object being to adjust tbe mean trajectory 
of tbe BATTERY, it must be wrong to range only with one or two 
guns as tbe process will then only give us the mean for the guns used. It 
was a practice that was very prevalent in the early days of the modern 
system of fire discipline and the two best layers in the battery were 
generally told off to the duty, but however satisfactory it may have 
been to the two guns concerned it was quite problematical whether the 
trajectory so established was suited to the laying and guns of the 
remainder of the battery. 
It is of course a great assistance, as a starting point, to know the 
actual distance in yards to the target, i.e . the real range, as this know¬ 
ledge T9 ill give us an approximation to the elevation required and 
eliminate the personal error in judging distance. This information may 
be got with a very small percentage of error, by the use of the range¬ 
finder, but as this instrument may not always be available and there 
are so many other factors, of such variable nature that have to be taken 
into consideration, which render it necessary that actual experiment 
should take place before efficient fire can be opened, that the question 
of ranging will first of all be considered by itself and then the amount 
of assistance to be derived from the use of the range-finder will be 
pointed out. 
The principal of these variable factors that influence the trajectory 
are : 
1. Variations in the performance of the powder, dependent on 
climatic and atmospheric conditions, which naturally vary, even 
from day to day. 
2. Force and direction of wind. 
3. Variations in the nature, etc. of the powder, owing to difficul¬ 
ties of manufacture, age, the amount of jolting about in the 
limber that it has received, etc. The following example is 
selected on account of the great care with which the laying 
was carried out, which shows that the result arose from the 
variation in powder. 
20 rounds 6*6-inch howitzer. 2 lbs. charge. Range about 
1100 yards. 
A single howitzer was used and was laid very carefully each 
time by clinometer. 
1 For selection of ranging point see chapter on “ Observation of Fire.” 
