HTF Vintage Calculator Circular Slide Rule Ruler Rapid Trigonometrical Indicator Circa 1960s

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HTF Vintage Calculator Circular Slide Rule Ruler Rapid Trigonometrical Indicator Circa 1960s
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Item - Vintage Calculator, "Rapid" Trigonometrical Indicator Slide Rule, Circa 1960s; used to look up 15 various geometrical formulae when working out triangular dimensions. The Single Sided Circular Slide Rule is made from two circles of plastic (celluloid) with a central metal rivet, allowing the disks to rotate. The smaller of the two disks is alligned to the required function on the edge of the larger disk - the formula can then be read through the wedge shaped window.

Maker - Rapid

Circa - 1960s

Construction -  Plastic

Country of Origin - Not Marked but believe to be English

Dimensions - 3" in diameter

Weight - 8 gram

Condition - Excellent Used Condition; there is though a very slight bit of rubbing from use towards the end of the word "INDICATOR" mainly over the 'TOR'.

Other Interesting Points - This particular slide rule is single sided with the scales as follows -

Side One - A, B, C, SINE a., CO.SINE.a., TAN a., CO. TAN.a., SECANT.a., CO.SECANT.a., SINE.b., CO.SINE.b., TAN.b., CO.TAN.b., SECANT.b., COSECANT.b., 

Side Two -

This particular type of slide rule is now becoming hard to find; we have seen a mint example with case sell in auction for just over 50.00 GB Pounds; but that was about 10 years ago......

Note regarding the pictures - Depending on your screen the slide rule may appear to look a little yellow but it is in fact the pictures.....the slide rule is more of a white/ivorine colour..... 

(Please see all Photos).


There is a charge of £1.00 for Postage and Packaging to all U.K. Residents (1st Class Mail Delivery, others P.O.A), we will also ship Worldwide please check table table below. If you have any questions please feel free to contact!

Postage Rates for this Item
Special Next Day Delivery £5.00
1st Class Recorded Mail £2.00
1st Class Mail £1.00
Air Mail Europe £1.50
Air Mail Outside Europe £2.00

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