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Re: Bygrave Scale Lengths-HR2 scales
From: Gary LaPook
Date: 2013 Jan 31, 02:22 -0800

BOY! now I am really confused! I took a close look at figure 29 and the cotan scale of the HR2 does not follow the pattern of the HR1 and Bygrave in that the values on the scale do NOT change by 0.1 log cotan per spiral. I am at a loss to explain how the scales on the HR2 can work.

You can see this for yourself. Take the log cotan of 81 degrees which is -0.80 so 7 spirals up (to the left) the log cotan should -1.50 which is 88° 11' but instead we find (in figure 29) 89° 19' which is log cotan -1.92. You see the same thing in figure 27, two spirals to the left of 20' should be 31' but is, instead, 42'.

Can anybody explain how this can work?

gl

--- On Thu, 1/31/13, Gary LaPook <garylapook@pacbell.net> wrote:

From: Gary LaPook <garylapook@pacbell.net>
Subject: [NavList 22190] Re: Re: Bygrave Scale Lengths
To: garylapook@pacbell.net
Date: Thursday, January 31, 2013, 1:07 AM

I just re-read you paper and I wonder if there is a slight error. You state that the inner tube of the HR2 has 27 spirals. Image 29 shows that the scale goes up to 89-40 and image 27 shows the scale goes all the way down to 20', (maybe even lower but I expect the photo was taken to the lowest end of the scale.) To cover that range requires 44 spirals like on the HR1 and Bygrave since the log cotan goes from 2.2 to -2.2 and each change of 0.1 requires a spiral, see: http://fer3.com/arc/m2.aspx/Bygrave-Scale-Lengths-LaPook-jan-2013-g22150 gl --- On Thu, 1/31/13, Ronald van Riet <ronald---nl> wrote: From: Ronald van Riet <ronald---nl> Subject: [NavList 22188] Re: Bygrave Scale Lengths To: garylapook---net Date: Thursday, January 31, 2013, 12:42 AM First to answer Gary's question about the scale length of the HR2: as my paper shows, it is about the same as that of the HR1, even though the item itself is much larger. This is mainly due to the numbers being horizontal to a vertical scale, therefore the windings of the scale are farther apart than on the HR1. But what I find expescially interesting in these pictures is the Werknummer of the HR2: 83989 which according to the black book should have been allocated to an HR1. I have just seen a picture of another HR2 with Werknummer 83995 which is in this same block of Werknummer. I am attaching a photocopy of the relevant page in the little black book: there is no mistake about it, it clearly says HR1! So this entire batch of 50 may have been HR2s, makes one wonder about the other entries in the same book. Please keep those HR1/MHR1/HR2 Werknummer coming!!! Ronald ---------------------------------------------------------------- NavList message boards and member settings: www.fer3.com/NavList Members may optionally receive posts by email. To cancel email delivery, send a message to NoMail[at]fer3.com ---------------------------------------------------------------- Attached File: 122188.hr1-entry-83951-84000.jpg : http://fer3.com/arc/m2.aspx?i=122188
: http://fer3.com/arc/m2.aspx?i=122190

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