# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Quartz article: reinstating celestial...
From: Robert Eno
Date: 2015 Oct 22, 09:25 -0600

Thanks Greg. I am going to crack open some books and have a look at this angle (no pun intended).

Robert

From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Greg Rudzinski
Sent: October-21-15 6:47 PM
To: enoid@northwestel.net
Subject: [NavList] Re: Quartz article: reinstating celestial...

Robert,

If you are a fan of the pocket trig calculator and Pub 211 then you should try substituting the Pub 211 A log value for sin and B log value for cos when performing a classic sin cos trig log sight reduction. This improves the arithmetic greatly.  If a table were made using  Pub 211 A B log values in the style of Hewitt Schlereth's table as seen in the back of his book Commonscense Celestial Navigation then a neat handy single compact table of about 35 pages is created.

Greg Rudzinski

From: Robert Eno
Date: 2015 Oct 21, 16:11 -0600

And excellent points from you too Lu.

I want to focus a bit on your comments about the organics of pre-calculator sight reduction and awareness of one’s surroundings.

This is absolutely true and it also extends to the arithmetic involved in sight reduction. By way of example, just for fun, I always reduce a few of my sights using the basic spherical trig formulas and a set of tables with logarithms and trig functions. After a bit of trial and error (as in figuring out how to manage logarithms of negative trig functions), I came up with a nice, neat system.  It has reached a point where I can “feel” if a number or result is just way off the mark. When I say “feel” I am not referring to some telepathic, hocus-pocus new-age thing. I mean that after reducing hundreds of sights and sub-consciously gaining an understanding of mathematical patterns, I can almost always detect errors before spitting out the final answer.  As in “no….that interim number is not right…..I need to go back and check my math or the entry argument”…Something along those lines.

This is not the case for electronic methods such as plugging numbers into a calculator and waiting for an answer.

All of which is to say that while I am still a proponent of electronic calculators, I firmly believe that one should be proficient with paper tables and with the multi-step hand-written process involved in reducing a sight. And further, I believe that HO 240 and HO 211 are the best emergency methods.

Does this make any sense?

Robert

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