The Caliper Slide Rule (or Slide View) watch is the second line of watches launched on Kickstarter by Caliper Timepieces of  Toronto, Ontario, Canada.  The watch retains the see through design of the brand’s first design, but this time adds a piece of history rarely seen or used in the 21st century, a circular slide rule.  Aviation and pilot watches in use today usually have specialized rotating bezels used primarily for flight related calculations where the slide rule is primarily an engineering tool.

Also known as an analog computer, the slide rule dates back to the 17th century and became an important tool for engineers in Europe in the mid and late 1800’s.  Surprisingly, slide rules did not become popular in the United States until the military used them in World War II and after the German rocket scientist Werner von Braun came to the US at the end of the war.  The slide rule became an important tool of NASA and the US space program and helped put a man on the moon.  With the introduction of the pocket digital calculator in the 1970’s, the slide rule quickly lost favor among engineers.

In this design, the slide rule is operated by a easy to grip 7 mm diamond grip 4 o’clock crown that screws down nicely, so it doesn’t move accidentally.  Caliper also includes a very nice separate metal circular slide rule with these watches.  Instructions on how to use the slide rule can be found with the watch and on the Caliper Timepieces website.  The 4.5 mm diamond grip 2 o’clock crown operates the 21 jewel non hacking Miyota 82S0 automatic movement. The movement operates at 21,600 bph and is specified to be accurate to -20/+40 seconds per day.  The movement is visible through the smoked glass window below the flat, slightly raised sapphire crystal on the front of the watch and the exhibition case back, surrounded by the engraved stainless steel screw down back,  The watch has a water resistance rating of 10 atm.

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The 316L case is IP (ion plated) with a form of PVD (physical vapor deposition) in a matt black finish that fits this design perfectly. The black on silver finish of the slide rule itself works perfectly with the simple all white hour and minute pencil hands, the white hour and minute markers on the smoked glass face and the blue matching second hand.  It’s interesting to note that the blue color of the second hand is used only on two triangular markers on the slide rule and on the stem of the larger 4 o’clock crown that operates the slide rule function. Only the faces of the two unsigned crowns have a gloss black finish.  Neither crown sits too low to the wrist.

This is a substantial watch but not huge and it hugs the wrist fairly well.  It is 43mm in diameter, 13 mm thick, 22 mm between the lugs and 50 mm lug to lug.  The case is flat on the sides, tapering inward towards the case back with a nicely finished groove about 2.75 mm below the top edge of the slightly rounded bezel.  The lugs are sharply defined, short and are totally compatible with the very comfortable matching finish mesh strap and signed, folding clasp.  I really appreciate this type of strap because it has far more adjustability and flexibility than a typical leather or rubber watch strap.

This is a unique watch that combines quality, comfort, attention to detail with a cool engineering tool vibe and function not easily found in today’s watch world. The watch will be available in the D1B model shown here as well as the A10 model which has a white on black slide rule with orange instead of blue highlights.  Retail price for the watch will be $500 USD.  A separate solid metal circular slide rule is included with each watch.  This project can be found on Kickstarter as well as at calipertimepieces.com

Bert Kanne is a freelance contributor to MBWW with a love for well made dive watches and chronographs. All photos by Bert Kanne unless otherwise noted.