RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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My introduction to a tesseract was during
an episode of Carl Sagan's "Cosmos"
series in the 1980s, where he was demonstrating how beings of dimension N would
perceive items of dimension N+1. The
explained, is a 3-dimensional projection of 4-dimension hypercube. Watch the embedded
video for more information.
The Tesseract website, which has nothing
to do with a hypercube as far as I can tell, deals in some very cool antique scientific
instruments. I learned of it from an article in
where an editor recommended it when researching the potential value of a collectible
telescope. Run by Drs. David and Yola Coffeen, Tesseract has a huge inventory of
items representing, among others,
Demonstration & Experimentation, and
"We are always interested in buying single items or collections. In addition
to buying and selling early instruments, we can perform formal appraisals of your
single instruments or whole collections, whether to determine fair market value
for donation, for insurance, for loss, etc. We were recently engaged to appraise
a major medical collection of several hundred items being donated to an American
museum, and to appraise a major European collection of early scientific instruments,
being insured for a loan exhibition."
The first item that caught my attention
were the "Napier" Rods, in the
list. Having heard of them but having no idea how they worked, I turned to
Invented by Scottish scientist
they are a mathematical multiplication aid that have markings such that the two
numbers for which the product is sought are constructed by laying the corresponding
'rods' side-by-side, and then the answer is obtained by adding the numbers residing
in common diagonal paths. It sounds complicated bu it really quite simple in practice.
As with using a slide rule, the user needs to keep track of decimal points during
calculation. You can take possession of this fine artifact for a mere $9,500. The
Calculation category also includes many varieties of slide rules (not just for mathematics),
sectors, scales, and other types of calculators.
Experimentation category has some of the coolest-looking contraptions and gizmos.
Many you have probably seen in the background of paintings of famous scientists,
mathematicians, astronomers, et al. Shown to the right is a set of early 19th century
official French standard weights that are fractions of a kilogram, for $3,800. On
the left is a "Gyroscope Compendium" set of gadgets used to demonstrate physics
principles. If you own one, it might be worth $4,500 according to the Tesseract
An interesting "Gear of Planets" is found in the
list. Although its exact date of construction is unknown, it obviously dates after
came up with the heliocentric planetary system (1543), but before
Pluto was discovered
by Clyde Tombaugh (1930) - although since Pluto was demoted to not-a-real-planet
status by the International Astronomical Union in 2006, its omission from the contraption
might mean it was actually made after 2006 (just kidding). Since the circular gear
for each planet is driven by a common long spur gear, the orbital periods are synchronously
proportional to the radii of each circle (circumference = 2π • radius).
I didn't take time to measure and estimate the accuracy of the model. It can be
a conversation piece for your display case for $950.
Tip: One of the best ways to view a website's collection of images without
having to click through a lot of individual pages is to do a Google image search using the site:etesseract.com
format in the search box.
Posted on April 28, 2016
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