Pickett Trig Conversion Model 903-T
The Model 903-T was produced in the United States since 1954. It was fabricated all aluminum, body parts hold with metallic braces, and all plastic cursor. I didn't found information about when the production of this rule ended or if it was replaced by other model, but in 1962 it was substantially modified. Pickett fabricated other rules with conversion capabilities, but only the model N909-ES Metric Conversion Simplex Trig has the same unit conversion operational concept as the original 903-T but less entries (16), all others, including the modified 1962-version, include tables with rule settings to perform such conversions plus a fraction-of-inch to decimal conversion table .
This rule was very well suited for science students and engineers. The scales on the 903-T are: K, A, DF [ CF, T Cot, S Cos, CI, C ] D, L on the front face, and on the back face four scales with gauge marks for unit conversion: LINEAR MEASURE [ LIQUID MEASURE, MISC. ] ENERGY MEASURE. The gauge marks on these four scales are equivalent to a 56-entries conversion table, while the conversion tables on other Pickett models have 30 to 32 entries only.
Besides the more unit-conversion entries on the 903-T, this rule does not require read instructions and set up the rule to perform the unit conversion, only oppose the gauge mark with one of the end marks, turn the rule and read the corresponding conversion on scales A-B or CF-DF,
The next arithmetic operations can be performed with two-three decimals precision with the 903-T model
SRPractice-1.pdfHere is the scan don by the International Slide Rule Museum of the User Manual to learn how to use the standard scales on this rule:
M51_Pickett_HowToUseTrigSlideRules_1960.pdf
