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Make Helix, United Kingdom (rule of Foreign manufacture)
Model Top Precision No. A101

1. Toward the end of the slide rule era, several companies started selling rules manufactured for themselves by others. (It had of course happened before, Post in the US being a notable example.) In some cases they were from manufacturers in the same country (Blundell rules in the UK appear under other names) and in other cases foreign. According to Peter Hopp Helix rules were made in Japan. This rule simply says "foreign" - this probably means Japan but other Japanese rules sold by British dealers that I have seen have had the word "Japan" blind-stamped somewhere.
2. I don't feel this rule is well designed. On the front of the slide it has a BI scale, not really very useful when you have both CI and DI scales. To use the trig scales, you have to reverse the slide but it has no C scale on that face, so you can't do calculations of the form a sin B / c. The sin scale has both sin and cos values marked on it, but all the numbers are in black. This makes it a bit confusing.
3. When I saw this rule in a shop I though "Aha! A rule I haven't got". It was only when I had second look at it outside that I realised it didn't have a cursor! If I was an American I would have said "Doh!" - in fact I think said something which if I was to repeat it here might get my site blocked by "family safe" browsing software. :-) .

Front view
1072-helix-A101-01.jpg (27135 bytes)
Detail - front left
1072-helix-A101-02.jpg (18367 bytes)
Detail - front right
1072-helix-A101-03.jpg (26833 bytes)
Detail - left- slide reversed
1072-helix-A101-04.jpg (8862 bytes)
Detail - right - slide reversed
1072-helix-A101-05.jpg (9268 bytes)
Manufacturing date c 1970
Length 10"
Material Plastic
Scales LL1, LL2, LL3, A [B, BI, CI, C / T2, T1, L, S] D, DI, K, LL0
Cursor Missing
Documentation None
Condition Very good apart from missing cursor!