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Gary LaPook

As memory serves, you had a recent article on using the slide rule in celestial navigations calculations, making particular reference to the use of slide rules whose trig scales read in degrees and minutes, rather than degrees and decimals, the more commonly encountered. Amongst seveal slide rules I have are the above mentioned, which read in degrees and minutes. Re them the following question. Looking at the S scale, with my old eyes, it appears that the scale is calibrated so that degrees and 30 minute increments are directly read, and 15 minute increments can be estimated accurately in 1 part of the scale. Other parts of the S scale can be read to 10 minutes, with 5 minutes estimated. The T scale seems similarly "loose". I presume that, as a practical matter, this degree of accuracy is adequate, though it seems "loose" to me.  Might I here be beating the proverbial dead horse? At your convenience, give me a shout please.

Happy holidays to you and yours.

Alan