||Helix, United Kingdom (rule of Foreign manufacture)
||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. :-) .
|Detail - front left
|Detail - front right
|Detail - left- slide reversed
|Detail - right - slide reversed
||LL1, LL2, LL3, A [B, BI, CI, C / T2, T1, L, S] D, DI, K, LL0
||Very good apart from missing cursor!