Category: Archive

Archive of favourited posts from various places.

Please note that from many sources, the content of a given post may be copied here in its entirety. None of the text below was written by me. Please see the original link for authorship.

Radio Signals from Mars, 1924

JF Ptak Science Books    Quick Post

Mars 1924[New York Times, September 18, 1921, here]

And so there came a time in 1923 and 1924 when it was determined that when the Earth next came into closest proximity with Mars (closest in opposition for a century) that efforts would be made to determine whether or not there was anyone around on that planet.  The idea of the radio being a powerful-enough instrument to be used in such a way was initiated in 1896 by Tesla, and soon followed at the turn of the century with support for the idea by Marconi  and Kelvin. (This interest was perhaps ignited after both Tesla and Marconi detected unexpected and steady signals that they thought were extraterrestrial but which were in fact ionospheric radiation–and of course there was Percival Lowell and his self-derived belief in Martian intelligence as described by the thought that there were canals on the surface of Mars.  

This was a massive-idea  effort:  a U.S. government initiative demanded five minutes of radio silence per hour over a 36-hour period in the vast hope that transmitters closed down that if there were any radio signals being directed towards the Earth from Mars that they could be more easily detectable.  

This was the magnificent “National Radio Silence Day”.  And it was extraordinary that i twas supposed to affect every radio in the country.

William F. Friedman, the Chief of the Code Section in the office of the Chief Signal Officer of the Army, was on the job and ready to decipher any messages that might need deciphering, which was some very hopeful thinking–not only was it hypothesized that there might be life but that it was also sufficiently advanced from some semi-primordial goo  as to have a technology capable of interplanetary communication, and that a code expert might be able to read anything that came in.  
 
Additionally that  New York Times article from 1921 described the proposals for the construction of a 60′ (720″) reflecting telescope–an absolutely enormous thing for the time, and for now, considering that the largest reflecting telescope yet built is 420″ (Gran Telescopio Canarias (GTC)), and that is a segmented scope, whereas this 720″ mirror-monster would have been one big piece of glass.  
 
But the country as a whole deserves a bit of credit for being so interested in the possibly of communicating with extraterrestrials that it was willing to let a main source of information and entertainment be interrupted for science, and that so many people had a hand in this. It was possibly one of the largest public experiments in the history of experimentation in the United States, and was also one of the earliest SETI attempts to search for intelligent extraterrestrial life.  

By: Ptak Science Books
Via: Feedbin Starred Entries
Source: http://j.mp/1CPQtQd

A Fine RADAR Map of NYC, 1946

JF Ptak Science Books   Quick Post

Radar map nyc

The history of RADAR (RAdio Deection And Ranging, and something I’ve always written in caps, for whatever that is worth) is absolutely not what I’m thinking about now–that is a long story with lots of twists and turns, complicated, complex–and it ranges depending upon location as for the most part RADAR (from the 1930’s anyway) was developed in secret, kept as a military secret.  And that’s because it was a very important development, with the victor of the Battle of the Beams being the possible victor, period.  

Radar246

All I want to do presently is note the significance of this particular pamphlet in the history of RADAR. This work was printed by PHILCO Corporation, (and dated January 4, 1946), and has an inserted leaflet stating that this “makes public for the first time the salient facts about the Corporation’s development and production of airborne radar equipment for the United States Army and Navy”.  PHILCO and other companies made significant contributions to the war capacity of the Allied forces, and–for this company in particular–much of that went unknown for quite some time afterwards, and of course there are some stories that just won’t get told. But for PHILCO the story gets told here.  

This is also a fabulous nighttime map of NYC–produced by RADAR.  

[RADAR on Wings, Philco, 1946.  10×8″, 30pp (unpaginated) with lots of photographs and an occasional schematic.  Available from this blog’s bookstore.]

By: Ptak Science Books
Via: Feedbin Starred Entries
Source: http://j.mp/1uC0IAt

Panoramic Periscope, 1915

JF Ptak Science Books   Quick Post

 
Periscope613good
This interesting and arresting images appears in Scientific American Supplement, October 23, 1915 (page 269).  It is an excellent view of topside from 30′ or so below.  The article describes simple, compound, tele-objective, direct-reflected, panoramic, and periscopes with annular fields–sort of simple, but not really.  In any event the panoramic periscope gave a view of a directed point-of-view as well as a slender (but versatile) 360o.

By: Ptak Science Books
Via: Feedbin Starred Entries
Source: http://j.mp/1yNZdo7