Keeping things in proportion

Inspired by an item I’ve recently discovered in the Bartholomew Archive Printing Record the time has come for me to stop glossing over some of the more complicated intricacies of maps and to tackle the art of scale. For those in the know, this is a simple and effective system to communicate the levels of detail within a map, but for everyone else it’s basically gibberish.

Bartholomew printed 2,235 copies of this sheet on the 28 April, 1891. It shows the four main scales that Ordnance Survey were using at the time and compares them by basically zooming out of a map centred on St Enoch’s Church in Glasgow.

The map appeared in the Scottish Geographical Magazine and accompanied a transcript of a paper read by Sir Charles Wilson at a meeting of the Society of Edinburgh. Sir Charles Wilson was the director general of Ordnance Survey at this time.

According to Wilson, between the years 1851-63, the Ordnance Survey was locked in the famous “Battle of the Scales” a battle that saw indecision regarding scale escalate to costs of about £30,000, a sum that would equate to over £2,000,000 today. But, eventually, a decision was reached and the four scales seen in these maps are four of the six that were settled on as the standard OS scales.

In a user friendly fashion they all have nice and friendly names, there’s the town plan scale, the parish, county and maybe less friendly, topographical scale. It might have been wisdom to end it there but unfortunately, for a science concerned with an accurate sense of place, vague names simply weren’t going to be good enough and so figures, ratios and fractions step in to complicate the picture.

So, now for my attempt at a step by step guide to understanding scale. The last map on the sheet is at the scale of 1:63,360. However, 1 what to 63,360 what’s? This of course isn’t made clear. Is it one inch or one millimetre, we just don’t know. What we do know however is that whatever one of them is on the map it’s 63,360 in real life. Luckily there is an alternative second name for this scale being one inch to the mile, simply, one inch on the map is a mile on the ground. You could of course use its alternative third name of topographic. But, if you’re wanting to speak in generalities why not opt for a generic ’small scale’ map? Because, even though you’re looking at a map with a scale of 1:63,360 this is a ’small scale’. The first map, at 1:500 is a ‘large scale’ map of course. So, 1:1 is huge and 1:1,000,000 is tiny. Confused? If not you’re clearly a genius but as for me, I think I’ll go back to studying the maps!