analog computer – slide rule plus a real life math problem debacle

slide rule w mechanical pencil for scale and leather case

I was rooting around in my miscellaneous keepsake drawer and pulled out this slide rule.  It was a Safety Recognition item from Canadian Bechtel Ltd., my late father’s old company.

I did not use this slide rule but instead a larger one in Grade 12 to solve Boyle’s Law Gas problems in my Chemistry class. That was in 1971.  My teacher, Fr. Donald Beaudois, S. J., offered my class an optonal after school tutorial in how to use a slide rule.  About ten out of 30 students took him up on his offer.  By allowing one to “ignore” the intermediate step in the calculation one could gain speed in getting to the final result.

from Wikipedia:

The mathematical equation for Boyle’s law is:     pV = k      where:

p denotes the pressure of the system.
V denotes the volume of the gas.
k is a constant value representative of the pressure and volume of the system.

Slide rules were developed in the 17th century based on the Logarithm work of John Napier by William Ougthred and others.  By 1974  with consumer-level scientific calculators available, slide rules quickly slipped into the past.

My Grade 12 Chemistry class marked the high water mark of my science education.  I must have paid extra attention that semester because I led the class with a 57 out of 60 on the exam.  I did miserably in math that Fall.  And that year marked my decision to turn from math and science to humanities subjects and I continued that direction in university.  The odd thing was that the following year, in Grade 13, we were given a scholastic aptitude test with three parts,  two English, one math.  I scored in the 99th percentile in both English parts, but surprisingly I managed a 86th percentile in the math portion.  Comparing results with other guys in my class–it was an all boys private high school–it emerged that some guys taking three maths and three sciences had scored as low as the 15th percentile.  Hard to say whether their trouble lay in doing well on scholastic aptitude tests or whether they were fighting an uphill battle and would run into insurmountable difficulties at the university level with math and science.  Several guys from that class went on to earn Ph. D degrees in the sciences. At any rate, I developed a bit of a math phobia around this time.  I believe I still sell short the math capabilities I have in my brain.

Real Life Math Problem Debacle

The one type of real life math use came up around 1980.  The Ontario Ministry of Education Library had a physical move to plan and execute.  I was a lowly clerk there, my second in a thankfully brief civil service career.  The math problem was the placement of the library shelf units.   Somehow I got assigned to figure this out.  Because I had some brains it seemed, I became the go to guy with special projects and problem solving.  The libarians concentrated on labelling and moving the contents of the shelves.  I decided that the equation was the following:

12x +  13y = n

where x equals the width of the 12 shelf units, y will equal the width of the aisle space between shelf units, and n equals the known total distance of the shelf unit area in the reorganization of the library.

Trouble was I trusted my boss when I asked her if all the shelf units were the same width. She said yes. The truth was that several shelf units with reference books, large books, were slightly larger.  Therefore when the movers came in overnight and placedf the shelf units as directed by calculation, we came in the next morning to find the last aisle unocomfortably narrow, which was followed by a solid wall.  My boss demanded an explanation.  I did some measuring and figured out that she had made the error and I had trusted her.  I could have checked the shelf widths, but she was the head librarian and I assumed she knew what she was talking about.   From the point of view of math problem solving I had the right idea, just bad data.

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