Showing posts with label theodore audel. Show all posts
Showing posts with label theodore audel. Show all posts

Friday, February 28, 2014

Wavelength Formula


In 1917 Audel & Co. published Hawkins Electrical Guide. There the formula for wavelength is described as follows:
"That point where the electric wharp and the magnetic flux meet, or the distance through space traveled during one oscillation cycle is considered the wave length..."
I'd always understood it just as the distance between peaks. The Hawkins definition remained the same through at least 1922 including that archaic use of the word "wharp." Wikipedia defines it very differently today.
"It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns."

This formula back in 1917 was given as W = 3.1416 x 2 x 2V √LxC. Given:
  • W = Wavelength in meters
  • V =  The velocity of light (186,600 miles per second)
  • L = Inductance in Henries
  • C = Capacity in farads.

You would think a century after the metric system they'd be using different metrics. Clearly this was an American edition. In that form I barely understand the formula. I would re-write that first bit as as "2π x 2V" but who's quibbling?  They're calculating frequency then multiplying by 2π. Today remnants of that formula can be seen in resonance calculations for LC circuits. Such as 1 ÷ 2π x LC. which calculates the resonant angular frequency. More here.

Today that same wavelength calculation is given much more succinctly as:
 λ = V ÷F. Given:
  • V = Wave speed/velocity (in meters per second, m/s)
  • F = Frequency in Hertz
  • λ =Wavelegnth in meters
It's amazing even today what the metric system has done for our understanding of even the things we already understood.

Thursday, April 08, 2010

Audel's Radiomans Guide

My copy was from 1946, faux leather, with 880 polished paper pages. It has a small paper tag in the back from Gimbel Brothers Book Store of Philadelphia; which no longer exists. It starts with radio principles, and covers everything from fundamentals to batteries, measurement, transformer, vacuum tubes, tuners, speakers, antennas, PA systems, radio navigation and at the end of the book even FM radio and TV. My edition opens with the following:
"This book, the author believes, will be of the utmost service, not only to the student and radio-electrician, but to anyone who wishes to be informed on this important field of science. Radio equipment cannot be services or maintained by any predetermined set of rules or formulae, but it is necessary rather to understand the principles of electricity, radio and sound..."
It's signed Edwin P. Anderson. He was born in 1895 meaning he wrote this text when he was 44 years old. He is credited as the author of no fewer than a dozen other Audel's manuals on refrigeration, air conditioning, gas engines, wiring diagrams, home appliances, electric motors, sheet metal working, millwrights & mechanics, television servicing, outboard motors, sewage disposal, a mechanical dictionary and others. Most of these can be bought for under $5 at Alibris. But not the Radioman's Guide. That one is spendy.

It was first published in 1939 by Theodore Audel & Co. Publishers 49 West 23rd Street New York, NY. Theodore Audel is a pen name. He wrote at least 10 of the Audels guides. His real name is Nehemiah Hawkins. He was born in 1833 and was an American inventor, publisher and author. he had several mechanical patents to his name. But he did not wrote The Radioman's Guide. He died in January 1928, a decade before the Radioman's guide was written. Though it undoubtedly contains information also in the earlier electrical guides that he did write. the earliest of which I confirmed was published no later than 1897 via Audels Publishing. More here.

The Theodore Audel & Co. Publishing company continued on into the early 1960s. They were purchased sometime in the early 1950s by American Handbook and Textbook Co. But in 1962 that parent company began negotiations with The Howard W. Sams and Co. for a buy out. The deal was completed in January 1963.

In 1967 the Howard W. Sams Company sold the company Howard W. Sams and subsidiary Audels to the ITT corporation. In 1985, ITT sold it off to Macmillan Publishing. In 1987, Macmillan was in turn bought out by the Maxwell Communication Corporation. Maxwell Corp chopped up the company and sold off many of it's varied divisions. In 1989 they sold off more. I am not certain in which fire sale, Audels was purchased. But there is a inference that two former Macmillan execs bought it privately only to sell it off to Bell Atlantic in 1995. In 2000 the company was sold again dotbomb named eCatalogs, who sold everything except the brand name. But after the crash they sold it to Sams Technical Publishing. I lost the trail there but the present owner is AGS Capital.

Despite all the paper shuffling, the Audels brand faded away. The Howard W. Sams Company updated and reprinted some of these classic texts by Anderson in the 1970s, and that was the end of things.