October 14th, 1899 letter from Nikola Tesla to George Scherff

Colorado Springs, Oct. 14, 1899

Dear Mr. Scherff,

I have expressed to-day some photos illustrating a few of my experiments here. One of them, as you will see is for my friend Mrs. Ledenbury (?) on 38th St. and Madison Ave. All the others for my friend, J. J. A. When you get these, open the box carefully and look over the photographs, be sure they are perfectly clean, then pack up nicely and deliver them yourself at the houses.

I want you to show them to Mr. Uhlman but not to others. Of course they must not go further. I am sorry to say the clockwork did not pan out right, besides, it is too big for a box I designed here. Mr. Uhlman should try to make the stop in the manner indicated by me, and all as small as possible. There is a finer clockwork to be had. He can make the lever to bear upon a disc of larger diameter, or stop the clockwork by a magnet in the manner of an escapement. This ought not to be difficult.

As to the point receiver, the chief is to have the points meeting in a very narrow tube and have the exhaustion 75 millimeters pressure, or perhaps 100 mm. The tube should be as in sketch.

Platinum wire sealed in glass all together, only very fine sharpened points (polished) exposed. The points as close together as possible, perhaps it would be best to make them actually touch, being very fine, I can burn the points off with the current off so as to level microscopical space between. Pressure 75-100 mm. To get the pressure right the glass blower should connect a tube to a gauge and seal off when the right pressure is obtained. I would like two tubes made like this:

A tube with 2 compartments, at a minute hole drilled through by a jeweler, a plate of aluminum and wire in each compartment. Tube about 1/4"-3/8" diameter. 1-2" long.

Sincerely,
N. Tesla