136 
SHORT NOTES ON PROFESSIONAL SUBJECTS. 
simple and of requiring no adjustment whatever. All that is necessary is to turn 
the sights on the water-line of a ship and read off on the face of the clinometer 
the required information as to elevation, length of fuze, &c. It is not even neces¬ 
sary for the gunners to trouble themselves about the range. 
The best plan to adopt is as follows :—The instrument having been constructed 
and set up, and the sights fixed on its face (which has been left blank), draw on 
the latter a sector of a circle, having its centre at the point of suspension of the 
plumb line. Within this sector construct a table according to the different natures 
of ordnance in the battery. In the accompanying figure the table is supposed to 
be for a battery of 68-pr. guns and 13-inch mortars. The line CD of the sector 
is, in general, placed at right angles to the line of sight. 
The headings having been filled in, as shewn in the figure, the calculated 
ranges corresponding to different angles of depression may be inserted, and the 
elevations, lengths of fuze, &c., &c., for each taken from the ordinary range tables. 
But a better way is to obtain all the information wanted by actual practice at 
floating targets. Thus, suppose a target to have been fixed at about 1500 yds. 
from the battery, the sights of the clinometer turned on it, and the plumb line to 
hang in the position AB\ a very few trial shots with each description of ordnance 
will be sufficient to enable us to fill in on the line AB all the elevations and 
lengths of fuze wanted. The target may then be moved a little further out or in, 
and the same process repeated, when we shall obtain the correct set of figures for 
