I have just finished Richard Holmes 'Shots from the front' The British Soldier 1914-1918. Before getting to the point of this post I would like to express the opinion that this book is one of the finest I have read dealing with the generalities of the Great War.
It is, of course, largely a book of pictures with supporting text. One of the pictures - Fig.71 - shows a sergeant of the RGA, a 60 pounder battery, taking notes from an artillery board. The board, chalk on a black surface, is not entirely clear in the picture. It presents in a tubulated form the detail of 5 targets. The column headings are; serial, switch ang, A of SShell, Fuze, Elev and Rate of F. I think I have a general, basic, understanding of gunnery but am floored by the the entires under 'Rate of F'
For each target there are 3 entries, 'Search', 'Sweep' and another illegible in the picture. Search for different targets has values of 200, 50 and 100, while sweep values for those targets are 25, 2 and 1 (not clear).
My question is what do the terms search and sweep mean?
Source: Artillery Board