9 May 2006

Kin sent me a message about the price of the day/night globe, which he got from The Discovery Store web site. He also included information about a perpetual motion globe that he saw at the museum store which I interpret to be referring to the American Museum of Natural History. The description he sent is from the Hammacker Schlemmer web site. I stopped off at their store on 57 St just off of Lexington Ave and found that they have two versions on display.

This is a really interesting globe. There are no batteries or electric wires involved. It runs off of normal room light (the salesman said it would be damaged by direct sunlight) that is collected by a photoreceptor in the globe. It converts that energy into a field that interacts with the Earth's gravitational field and causes the globe to rotate. I suspect that there is a gyroscope inside the globe that is causing the spin. The globe is surrounded by a low viscosity fluid to reduce friction, and sealed in another clear globe. It all sits on the points of three inclined acrylic dowels. I was able to hold it and felt nothing but its weight. But it kept spinning as I held it.

I didn't think to ask if it stopped rotating when the room is dark or if it can be tipped at 22.5° to simulate the inclination of Earth's axis. I suspect that the answer to both questions is no. I think it is doubtful that a gyroscope could be made efficient enough to store enough energy to work overnight. And there are no batteries to store the electricity generated to make it available to some other type of device when it is dark. And since the globe is suspended in the outer sphere I think it is weighted so that the South Pole will always point toward Earth's center of gravity. I will need to make another stop there to continue my research.

Another thing that is interesting is the outer globe. I didn't detect any seams where the halves of it were joined. It looked like the inside globe was what you were holding. There were no air bubbles at the top of the globe. How do you fill a globe with a fluid and seal it without getting bubbles inside. With the precision workmanship that goes into creating these globes I can see how they can get $500 for them. But I would have to be very rich before I could spend that on a 9" globe,

This globe is available in either political or geophysical versions.

They also have on display an Earth in a clear celestial sphere with a Moon that you can manually rotate around it. It is one of the ones where you have to look through the sphere to to constellations printed on the oposite side to see them in their proper shape. It is actually a 3D planisphere since you can set the date and time to see what you can see in the heavens.

There was a card on display for the Celestron SkyScout but said they haven't received it into inventory yet. I thought it was supposed to have shipped in March but maybe it is May. Or maybe the production schedule has slipped as I believe it has before.

From Kin:

FYI:

http://www.discovery.com/
BEST SELLER
Illuminated Universe Globe
#729251
$79.95
IN STOCK
-=-=--=-=--=-
I want the one below though. I was very impressed when i saw this in the museum.

The Perpetual Motion Rotating Globe This is the worlds most advanced globe, capable of continuously rotating on its own without any need for human contact, cords, or batteries, and most faithfully recreating the earths rotation in space right at your desktop. Developed in the U.S. over six years by a team of physicists and artists, the globe operates in apparent violation of the laws of thermodynamics, which state that perpetual motion is impossible. The globe encloses a photoreceptor that gathers room light to power an internal drive that spins the globe by means of a force from the earth's magnetic field. The globe consumes a mere .1 microwatts (1/10th of 1 millionth of a watt) of power, an infinitesimal amount that would normally be too small to move an object of the globes weight, unless the drag forces were also infinitesimal. The globe is suspended in a clear liquid inside a clear acrylic shell: the liquid reduces friction against the globe, allowing it to rotate continuously and silently at a steady, gentle pace, exactly the way the earth rotates in space. The globe can even be held in the hand and it will continue to spin. The internal mechanism is imperceptible beneath the globes colorful surface that shows a political map with topographical shading, major cities and countries, and bodies of water labeled. Prolonged exposure to sunlight should be avoided. 9" H (with stand) x 6 1/2" Diam. (4 1/2 lbs.)

Item 72372 ................... $499.95

http://www.hammacher.com/publish/
72372.asp?source=overture
&keyword=spinning%20globe
&cm_ven=NewGate&cm_cat=overture
&cm_pla=Holiday%20Preview05
&cm_ite=spinning%20globe