Pickett N4 and its Base-10 LL Scales

[@Ensign_Cthulhu]

I am holding in my hand a Pickett Model No. 4 in a sort of pale beige colour, which is like the one you are demonstrating except that it doesn't have the Ln scale. I haven't touched it in years and I'm very grateful to you for this quick tour of it. I started out as a Pickett man - the first slide rule I bought was one of the late plastic ones - but I came around to K&E and Hemmi as time went on. I agree with you that Pickett tried to squeeze on a few too many features! Alas, my 20 inch K&E deci-trig duplex came with a rotten cursor (a known, increasingly common problem!) and broken glass. I'm going to have to see if I can buy a new cursor for it somewhere.

[@jadenephrite]

Regarding 5:13, Ln Scale for Natural Logarithms. The way I remember the relationship between Natural Logarithms to Common Logarithms is to look at the right end index of the Ln scale to see its corresponding value on the L scale. At the right end index, the Natural logarithm of 10 on the Ln scale = 2.3026 on the L scale, because the Natural logarithm of 10 = 2.3026. This is known as the Modulus "M" conversion factor from Natural Logarithms to Common Logarithms. Therefore to convert a Natural logarithm to a Common logarithm, simply multiply by 2.3026. On the other hand, the reciprocal of M is 1/M = 1/2.3026 = 0.4343. 1/M is used to convert a Common logarithm into a Natural logarithm. This is because the Common Logarithm of e = 0.4343. On the Ln scale, 1 has a corresponding value of 0.4343 on the L scale.

[@robinj.9329]

I have two of these Pickett N4 rules. There are so many calculations possible! It would take me years to master them all. As a kid in High School in the 60's I thought I was a real "Wiz" with the sliderule. But I never owned one like this. The one's in my collection are recently acquired.

[@MarkKrebs]

Thanks for an instructive tour as always. I learn something every time.

[@738polarbear]

Great job sir.

[@mustafatechnicalsaab8934]

It's so beautiful it looks like slide rule in Cassie is used to calculate the position of the moon in a movie Moon fall 🌚❤

[@MarkKrebs]

Anybody venture a guess why they'd do this? I like the quick conversion to dB so maybe that's the reason, but the price we pay is loss of A&B. Why not just DF/m, a single scale and Keep A&B? That wouldn've been great. Also why hyperbolic trig? What calculation was everybody doing that wanted those functions? Should be a Comms. topic because of the dB to tie it into the common logs?

[@ProfessorHerning]

It does sound like the N3 is the slide rule for you. I wouldn't lament the loss of base-10 logs for quick dB calculations that much. The L scale is not too hard to use (or just use LL and divide the natural log by 2.3 [~ln(10)]).

[@ProfessorHerning]

or use the nethod I mentioned in the other post which finds the log on C. (LOL).

[@viarnay]

At that distance leave the camera focus fixed

[@riadriddick1680]

AVENDRE: J'ai 140 règles de calcul tout neuf N°57/88-Reitz-N-Etudiant & N°57/89-ETUDIANT LOG LOG.Fabrication allemagne en 1965.

[@phasorsystems6873]

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