As promised in the previous post, some scans on the angle measuring instructions that came with my “Italian Army” compass.
![](http://survive.phillosoph.com/wp-content/uploads/2016/11/compassmanual1-300x197.png)
The first paragraph refers to the clinometer. If you work in certain fields the contents of column V will be familiar to you. This column can be read as either fractions or gradients. That is, for example, 25% = ¼ = 1 in 4. A slope of 14° therefore drops or rises one metre for every four metres of horizontal distance. A 45° slope is 1/1 so changes by a metre for every horizontal metre.
In the illustrated example below a hilltop is measures as being at 14° to the viewer so its height must be a quarter of the distance between the two. The converse is also true. If you know the height of an object and can measure the angle you can calculate the distance. A building storey is 3 metres so a three story building will be 9 metres. If the observed angle to the top of the third storey is 6° then the distance must be 90 (9 x 10) metres.
The same system can be used with horizontal angles, taken from bearings of each side of an object. Also illustrated is a way to use the graduations on the window in the cover to calculate the distance from an object of known width.