This miniature key is also known as the "73" key. It is a covered
bug and came in several variations in size and color. Chrome, black
wrinkle, and a blue cover were produced. The chrome key here is quite
a bit smaller than the black wrinkle one. Apparently, these keys were
meant to be portable, though they would seem to be too heavy and awkward
for that. Some "73" keys had a hinged cover, others had completely
detachable covers. The name "73" key came from the number on the top
of the cover.
Distance and True Bearing from Your Lattitude and Longitude
This program lets you enter your position
and using trigonometry it calculates the distance and bearing
to most other countries in statute miles. Northern
lattitudes are positive, southern are entered as negative. Similarly,
westerly longitudes are positive and easterly longitudes are negative. Adapted from the ARRL
Antenna Handbook, 14th edition, page 16-4. Set your lattitude on the
top scrollbar. Set your longitude on the middle scrollbar. Scroll
the bottom bar to the desired destination and read the distance and
bearing from your location. The initial lattitude and longitude are
set for Silver City, NM.
How Much Does Air Weigh?
To ordinary observation, air is scarcely perceptible. But SCUBA divers know that a SCUBA tank with compressed air in it before a dive is alot heavier to carry than one that is empty after a dive. But how much does air weigh? We can use our virtual scale to find out. The left side has a SCUBA tank on it which starts out empty. The scale has been tared to cancel out the empty weight of the tank. The pan on the right side starts out empty. Each left click on the SCUBA tank adds a cubic foot of compressed air, and a right click on the SCUBA tank lets out a cubic foot of compressed air. Left clicking on the pan on the right adds a pound of weight, while right clicking on the pan removes a pound of weight. Experimenting with the virtual scale will show that it takes 12 cubic feet of air to weigh a pound. Thus this SCUBA tank holding 72 cubic feet of air gains six pounds after being filled. The air in a room 60 feet by 30 feet by 15 feet weighs more than a ton! Adapted from 'A First Course in Physics', by Gale and Milliken.