3.7" ? at Macaulay Plain, Esquimalt, Victoria, BC 1943

[Jon McGrath]

Many thanks Brian! I had a quick look at the document and will read it more closely later this week. As you say, it provides a wealth of information on the BC AA defences. I know my dad was stationed in Tofino, Point Grey (Vancouver), Ambleside (West Vacnouver), Little Mounttain (Vancouver), Sea Island (Vancouver/ Richmond) and, of course, MacCaulay (Esquimalt) - all mentioned in the document. A lot of movement. As the Japanese threat disappeared, he was sent to the UK for infantry training. Then back to AA post-war.

[maple_leaf_eh]

By coincidence I was working on a lesson plan about Mapping and Charting Establishment's 110 yrs of history. One point was that mappers in Canada had surveyed 59 coastal defence artillery positions during the war. They were quite proud they had 2' contour lines around the batteries. The rule of thumb is that the horizontal accuracy of a map is 1/2 the contour interval.

[rob love]

Originally Posted by maple_leaf_eh

By coincidence I was working on a lesson plan about Mapping and Charting Establishment's 110 yrs of history. One point was that mappers in Canada had surveyed 59 coastal defence artillery positions during the war. They were quite proud they had 2' contour lines around the batteries. The rule of thumb is that the horizontal accuracy of a map is 1/2 the contour interval.

I guess I have been out of the military and away from the maps too long cause I have no idea what the heck that last sentence said.

[maple_leaf_eh]

Rob, that means everything drawn on the map was supposed to be within 1' of its "real" location. Most 1:50,000 maps are only a 20m interval, so things are more or less within 10m of reality.

[chris vickery]

So, in other words, 1' is pretty darn accurate...