# Pocket Calculator

My father started his career around 1955. He began as a draftsman. As you might expect his tools-of-the-trade were pens, pencils, a drafting table, T-squares, triangles, scales, etc. For mathematical computations he used a Keuffel & Esser Co. N4083-3 Log Log Duplex Vector slide rule. (The Cadillac of slide rules.) This slide rule was copyrighted in 1947 the same year as the invention of the point-contact transistor - the first solid state electronic transistor. These transistors, along with other advances, would eventually lead to the development of the electronic calculator which would replace the slide rule.

The slide rule or “slipstick” is a mechanical analog computer used for multiplication, division, logarithms, exponents, roots, and trigonometry. Slide rules use logarithmic scales which allows products to be derived by adding the log of a numbers and quotients are derived by subtracting the logs of numbers. It simplifies and accelerates mathematical computations.

The slide rule enabled a prototype of the P-51 Mustang to be rolled out 102 days after the contract was signed. It was also the computational tool that put a man on the moon. My dad used a slide rule for construction and engineering projects. His slipstick helped him start his career and raise a family.

Most of you reading this will have no idea what a slide rule is or how to use one. Me either although my brother showed me how when I was in high school. However I have my father’s slide rule. It is sitting on my desk right next to the (modern) computer I use to write these words (and later post this blog).

My brother gave me dad’s slide rule for Christmas this last year. He had kept it all these years, had it refurbished, and presented to me because he knew I would appreciate the “elegant technical beauty”. He hoped I would “feel the emotional connection with dad and treasure it as I have.” As I held the slide rule and read his words, the emotional connection brought tears to my eyes. A thoughtful gift I will cherish until I cannot.

I started my career around 1988 working on construction and engineering projects. I began as a consulting engineer which, at the time, required me to use pencils, drafting table, T-squares, triangles, scales, etc. as my tool-of-the-trade. For mathematical computation I used a Hewlett-Packard HP-41CV. (The Cadillac of electronic calculators. Yes, I know the HP-41CX was the top-of-the-line.) My calculator helped me start my career and raise a family.

My son, my daughter, and my son-in-law have all used electronic calculators but they started their careers with smart phones and personal computers. In the case of my son-in-law, he uses these tools working on construction and engineering projects.

The tools may change but our need to quantify things in our life is enduring