Pickett Model N 3

The Pickett Model N 3 "Power Log Exponential -- Log Log Dual Base" slide rule is one of the most powerful general-use rules in the Pickett line. The N in the name stands for "New" to distinguish from its predecessor, the Model 3.

Model N 3-T

Type	Slide Rule
Manufacturer	Pickett
Introduced	c. 1960
Discontinued	1975
Predecessor	Model 3
Cost	$26.95
Calculator
Precision	3 to 4 significant digits
Display type	Analogue scales, sliding cursor (white body)
Display size	10"
Programming
Other
Dimensions	12" long

Model N 3P-T

Manufacturer	Pickett
Introduced	C. 1959
Discontinued	1975
Cost	$13.95
Calculator
Precision	2 to 3 significant digits
Display type	Analogue scales, sliding cursor (white body)
Display size	5"
Programming
Other
Dimensions	7.5" long

Overview

Model N 3-ES

Type	Slide Rule
Manufacturer	Pickett
Introduced	1960
Discontinued	1975
Predecessor	Model 3
Cost	$26.95
Calculator
Precision	3 to 4 significant digits
Display type	Analogue scales, sliding cursor (yellow body)
Display size	10"
Programming
Other
Dimensions	12" long

The Model N 3 series of slide rules are a set of high end engineering rules that represent the height of Pickett's production. They boast the second greatest number of scales for any of Pickett's offerings at 32 total scales, second only to the N 4 vector rule's 34. The N 3 is composed of an aluminum body and slide, with a nylon and plastic cursor, which is unusual for most slide rules, but allowed Pickett rules to have a very clear, very precise face which is easy to read.

Colors

Pickett models after the introduction their "N" family represented a transition between preferred colors, with most "N" rules coming in both original white (denoted by a suffix "T") and their patented "Eye Saver" yellow (denoted ES). Functionally, the only difference between the models was their variation in color, and all significant components remained functionally identical.

N 3

Model N 3P-ES

Manufacturer	Pickett
Introduced	C. 1960
Discontinued	1975
Cost	$13.95
Calculator
Precision	2 to 3 significant digits
Display type	Analogue scales, sliding cursor (yellow body)
Display size	5"
Programming
Other
Dimensions	7.5" long

The N 3 came in both white and Eye Saver Yellow, and has a standard scale length of ten inches. It is characterized as a "dual base" rule, meaning it is capable of evaluating both common and natural logarithms. It has a common complement of scales known to most engineering rules described as "log-log" rules, which allow it to perform a wider array of functions such as hyperbolic trig and arbitrary exponents much easier than a more simple rule. The N 3 is considered one of the quintessential duplex rules, being one of the most versatile rules available.

N 3P

The smaller brother of the N 3, the N 3P has all the same scales, and therefore the same functionality as the original N 3, but in a "pocket" form factor. The smaller size of only five inch scales necessarily comes with a loss in accuracy, as with all analogue calculators, but in most cases can give answers accurate enough for any field work or quick estimates one may need. With careful planning and estimation, some users can even gain a fourth significant digit out of it in certain cases. The N 3P also came in both white and ES Yellow colors, with the white being increasingly rare in most markets.

Scales

The N 3 and N 3P both have identical scales and layout as duplex engineering rules. They have the common set of scales for most engineering rules of the day, but also a few unusual scales which give a slight edge over competitors, such as the extended cube root scales, and the inverted DI scale on the body of the rule.

Layout

The N 3 series is a duplex rule, with "Log Log" layout, also called an engineering layout. The N 3 has two "subtitles," both of which describe the layout of the rule.

Power Log Exponential

Also later described as "exponential speed rule," this describes the log-log scales being laid "back-to-back" so that the reciprocal of a number lies directly below the number itself on the same scale. This speeds up processes like hyperbolic trig, or finding reciprocals of very small or very large numbers.

Log Log Dual Base

This description says that the rule has both natural logs as well as common logs (base ten) as scales on the rule. In the particular case of the N 3, the log-log scales (LL) are keyed in base e, with an additional log scale (Ln) denoting the log of the associated C scale value. The Natural log and Common log scales are placed back to back in a "speed rule" format to facilitate easier transition between them.

Pickett rules in particular are known for their unique back-to-back "speed rule" features. This is common across most of their log-log rules, which have both ascending and reciprocal LL scales back to back, here marked with a ±. Other scales arranged as such are separated by a slash "/" to show that they are connected. Scales that lie on the same divisions are marked by a hyphen "-."

Front

√_1/2 K A (B ST/S-Cos T/T CI C) D DI ³√₁ ³√_2/3

Back

LL0± LL1± DF (CF CIF Ln/L CI C) D LL2± LL3±

Differences from Model 3

The N 3 and the earlier Model 3 share many similarities between scales with a few notable changes for the N series version. Primarily, the Model 3 lacks the "speed rule" back-to-back scales that are ubiquitous on the N series rules. Instead, the reciprocal log log scales are grouped together on one half of the body, while the main LL scales lie on the other half. Additionally, the base for the LL scales of the model 3 is base 10 (the common log) as opposed to base e (the natural log), which gives a different range of possible values on the scale. Finally, because of this different base, the folded scales on the LL side of the model 3 are folded at approximately 2.3, which allows for quick conversion between natural logs and common logs. The model 3 has fewer scales on the slide, and instead makes room on the back for tables which help the user place the decimal point appropriately, which must be done mentally on slide rules and can be quite challenging for those not familiar with slide rule use.