-------- Original Message --------
Subject: Re: question about determining scale
Date: Thu, 12 Dec 2013 10:00:26 -0500 (EST)
From: Paige G. Andrew <[log in to unmask]>
To: Air Photo Maps, GIS Forum - Map Librarianship <[log in to unmask]>


Manon,
Â
I'm not certain that there is any kind of rule about rounding up or down in such cases, so my guess is whomever created the example simply made one choice over the other. In any case, in the relative scheme of things, would either choice matter a lot "on the ground"?
Â
Paige

From: "Angie Cope, American Geographical Society Library, UW Milwaukee" <[log in to unmask]>
To: [log in to unmask]
Sent: Thursday, December 12, 2013 7:52:34 AM
Subject: question about determining scale


-------- Original Message --------
Subject: question about determining scale
Date: Tue, 10 Dec 2013 18:23:02 -0500
From: Manon Theroux <[log in to unmask]>
To: [log in to unmask]


For those of you familiar with the "Cartographic Materials" rules for cataloging maps, I have a question about determining a representative fraction using a bar scale. I've copied below example #2 from Appendix B (Guidelines to Determine Scale and Coordinates), B2B (Conversion from a graphic scale). I don't know if the formatting will come through or not, so you might have to check your copy of CM. When I try to replicate the math, my calculator gives me "63,1578947368" for the right hand side. Rounding that off would give me a representative fraction of 1:63,158. Can anyone explain why CM gives 1:63,157 as the RF? Is there a reason you would round down?

Also, I'm curious, how likely is it that a map cataloger would have a ruler that measures to the accuracy of 1.14 inches anyway?

Thanks in advance for any help you can provide,

Manon Theroux
Head of Technical Services
U.S. Senate LibraryÂ

------------------------------

2 000 yards in units of the bar scaleÂ
measure 1.14 inches with a ruler.
1.14 inches (on map) represents 2 000 yards (Earth)
2 000 yards = 2 000 × 36 inches
The ratio is: 1.14a2 000 × 36)

   or
   or
   1:63 157Â