Svar said:
Packard said:
I am reminded of the very pricy bamboo slide rule (with plastic facings). The crosshair was purported to be a black widow spider's web stretched and glued to the plastic because it was impossible (back then) to mill a fine enough groove for the cross-hair.
Spider's web? This is odd. Would black hair be easier to obtain? Regardless, there is no need for milling. Just slice/scratch it with sharp blade, make it as fine as you want.
I found this reference from Wiki, so the black widow's web might be true after all.
Originally crosshairs were constructed out of hair or spiderweb, these materials being sufficiently thin and strong. Many modern scopes use wire crosshairs, which can be flattened to various degrees to change the width.
I looked online for verification and could not find it. Perhaps the spiderweb story was apocryphal. But in 1967 I bought it, almost new in the original packaging from an engineering student in financial crisis for (as I recall) the outlandish price of $75.00. For $75.00 I darn well had better have gotten a genuine black widow's spider web filament for the crosshair.
(I just checked with CPI inflation calculator and that $75.00 in 1967 is $633.62 in 2021 dollars.)
In 1972 my sister bought the first available Hewlett-Packard scientific calculator and never picked up the slide rule ever again. If you have ever used log tables, you will understand why.
By the way that rudimentary calculator cost $400.00 in 1972--about $2,700.00 in today's money. You can buy the same performance from a $30.00 calculator today.
As a side note, Post (the slide ruler maker) called the indicator a "cursor" back then. I always thought it was a computer term.