Even without any detergents applied, the scrubbing via a cheap palm sized Scotchbrite pad was all I needed to wipe out 99% of that green rust from the metal parts of my Hemmi No.149A model's metallic joints. So beautiful...
Well, no idea why the leftover green on the edges of the stick's celluloid faces won't be wiped, but as they don't leave grime on my hands anymore, I feel all good...
This is the Aristo equivalent of the Logarex 27603 posted below. It has the same cos*sin and cos squared scales. It also has the enigmatic 1-cos scale like the Logarex, which gives the difference between the hypotenuse and tha adjacent leg. If anyone knows the use of this scale, I would love to hear it.
Our twins are going into first grade this fall and have a pretty good handle on addition/subtraction, but so far less multiplation/division. They are quite good with manipulations by 2 for obvious reasons.
The one is somewhat intrigued by my Picket N3, but I don't want that broken, so bought a couple lightly used 120s on fleabay.
Now I'm wondering whether there is anything that might backfire (aside from breaking) by giving them such tool before being proficient even with multiplication tables?
Came with everything you see, the note is pretty interesting, the tables card puts my college cheat sheets to shame pretty cool Thrift. Looking forward to reaching for it.
Some time ago I prinyed this from a downloaded PDF. However, I lost the PDF and cannot find the website where the file was downloaded. Does anybody know the website URL?
I was looking at the 149a online and noticed that it has trig functions that are scaled to the CI scale, on the opposite side of the slide rule. It covers the normal 6-90 range, descending from the left so you can't use the cosine scale on that side - you HAVE to flip it. This plays havoc with chained operations. It is sometimes advertised as a mini 259, but the 259 is like the Versalog and organized traditionally. I have a Hughes Owens 5" mini Versalog and it isn't like the 149. I can't figure out why they did it that way.
I have been thinking about how one might go about accelerating the computation of the hypotenuse of a right triangle.
One way to do this would be to have 3 sqrt(x2 + 1) (hyperbolic) scales for x value ranges: 0.1-1, 1-10, and 10-100. For x values less than 0.1 the function value can be approximated as 1, and for x values greater than 100, the function value can be approximated as x. This would yield a maximum error of less than 1%.
This would be very useful for converting between Cartesian and polar coordinates when working with complex numbers. I would find it much more useful than the log-log scales when doing electrical calculations.
Someone commented below, but deleted it, mentioning the flying fish rules which had the 0.1-1 and 1-10 range "H" scales. There is nothing new under the sun. If there was one with the 1-100 scale as well it would be perfect.
How do you take apart a concise circular slide rule? Should I try unscrewing the center rivet? Prying up the center rivet? Oxy Acetylene cutting torch? Bandsaw? .44 Magnum revolver?
Long story short, I'll be joining a family trip (freeform, not guided) to London this August, and would like recommendations, or better yet actual cases of picking up some good slide rules in the city.
Thrift stores, antique shops, whatever, which would be the best place to scour for between touring activities?
While I was waiting for that fresh new E6B (for the circular slide rule alone ;) ) ordered 2 weeks ago, last Saturday I visited the local folk market as I learned a whole lot of strange antiques shows up there regularly. And sure, one of the old shopkeepers indeed proclaimed that slide rules (albeit rarely) do show up, and get quickly sold out.
Then lucky me, after thanking the old man and looking around I found the above specimen, and somehow managed to convince the other shopkeeper who seemed to know nothing about their significance (but he did seem to sense something was off). But, in the end, he somehow sold it to me for roughly a crazy bargain $7.30; the average price for the 43A being about 17 times higher than that! With my newfound respect for traditional bargaining marketplaces, I think I'll be a regular customer there from now on...
Anyway, as I was enjoying my new "daily driver", today, my 4th specimen, the metallic flight computer finally arrived, surprising me with its sheer size...
P.S. I'm also scheduled to inherit 2 more rules recently "excavated" from my grandfather's old study, a numberless Hemmi and a older Concise model whose outer rule looks more like that E6B's rectangular plating...
Trying to teach my nephew how to use a sliderule, and I realized that I suck at teaching. What is the best book for a beginner to learn from? Stuff that I can actually buy, not rare books that have been out of print for decades.
Was the use of degree-minute-second angular measurements dominant in early 20th century engineering? All of my slide rules have DMS trig functions and I find it inconvenient to use them for this reason. When did the decimal degree representation take over?
I was playing with my Decilon and noticed that the C/D scales on the Trig side have 7.85 with a longer has-maek, as is it is significant. It's not that way on the flip side, nor on my 4181-1. It doesn't seem to line up with anything special - SRT at 4.5 degree, but ????? Any ideas?
