Eastern Science Supply Co. Heliostat

Background
Description
Photos
Related
Patents
References
Links

Background

For a very long time I've had an interest in Heliostats (Wiki). I think that's what this is. Made by Eastern Science Supply Co. (ESSCo), Boston Mass. I expect it was intended as an astronomy demonstration device, but not sure. Have a book on order "Study, Measure Experiment, stories of Scientific Instruments at Dartmouth College" which may have some information. If you know about this please contact me.

This instrument has the look and feel of the Mance Type Mk V Heliograph. The purpose of the Heliograph is signaling whereas the purpose of the Heliostat is to aim the Sun's beam at a fixed target.

This instrument appears to be more modern that the Viennese instrument of 1850 shown on the Wiki Heliostat web page. It's missing the plumb bob for the latitude scale, you can see the hole where it should attach.

Description

This may more correctly be called a type 1 coelostat (Wiki, Red Rock) because it has two mirrors.

The base has a couple of level vials so that the horizontal tilt axis will be level. There is a latitude scale allowing the main rotation axis to be set so it points to the celestial pole. There is a clockwork mechanism to rotate the mirrors to de-spin the Earth. The adjustable length mirror support rods and the top mirror can be rotated relative to the base by using the thumb screw on the top of the clockwork. This allows aiming the top mirror in hour angle. The bottom mirror should be driven by the clockwork, but appears to move free. Probably something inside is loose or broken. On the bottom of the clockwork there is a key to wind the mainspring, but it's tight, i.e. the spring is fully wound. There is also a rate adjustment. In the center bottom there's a thumb screw that directly turns the clockwork output shaft.

There is a threaded hole at the center of the base, but it's too small for a 5/8-11 surveying tripod and too big (about 1/2") for either a 1/4-20 or 3/8-16 European camera tripod. Probably made before these were standardized.

The reason that the mirror moved freely was that it's pinch screw was not tightened to the shaft.

1 July 2016 cleaned & oiled, now running. After a couple of shots of Berryman's B-12 it started running. Oiled with Nye Clock Oil 140B.
It's going to take some hours for the mainspring to open so that Mobil 1 oil can be worked into the flats. Am applying Mobil 1 to the mainspring as it winds down.

After 22 hours it's still ticking. But the mainspring looks almost unwound.

Photos

Fig 1 Top Overall View

Fig 2 Bottom View
Fig 3 Clockwork
Marked:
Waterbury Clock Co.
Made in USA

Operation Photos

Fig 4
At first setup with hour angle pointer in night half of 24 hour
clock, but it should be in the daylight half.

Fig 5
Rotating mirror flipped over and the central knob used to turn
mirror 180 degrees, now you can see pointer is at about 10:00
while the house clock says about 11:30.
Fig 6
Closeup of heliostat showing time pointer.

Fig 7 about an hour later
The spot has moved but a little less than 15 degrees.
Note you can see the pointer tip illuminated by the sun.
But the pointer is not pointing exactly away from the sun,
so the hour angle is not set properly. This demonstrates the
interrelationship between the LMST and north azimuth.

After 3 hours the spot has moved left and down a total
distance of about 3 feet. The distance from the heliostat
to the spot is about 36 feet. An angle of less than 5 deg.
The sun moves 15 deg/hour so has moved 45 deg.
Better initial alignment would reduce the spot movement.

Astronomy

Patents

----------------Waterbury Clock Co. ---------------
Waterbury has many clock related patents. This mechanism makes use of 3 of their Lantern-pinions. Since the patent was filed in 1904 the was probably made after that date?
787041, Lantern-pinion, Ernest H Horn, Waterbury Clock Co, Apr 11, 1905, 368/322; 968/93 -
1440426 Pivotal guard for clock springs, Frederick Wehinger, Waterbury Clock Co, Jan 2, 1923, 368/141, 968/377 - Maybe made after filing date Sep 29, 1922?
1546075 Balance-staff bearing for timepieces, Horn Ernest H, Waterbury Clock Co, Jul 14, 1925, 368/324, 968/278, 384/244 -

------------------------ Heliostat --------------------
31060 Enlarging Photographic Pictures, John H. Whitley, Jan 1, 1861, 353/3 - requires Sun tracking
54118 Arrangement of solar mirror for photographic purposes, Apr 24, 1866, 353/3 -
59438 Solar Camera, L. F. Moeawetz, Nov 6, 1866, 353/3 -
514669 Heliomotor, Luther W. Allingham, Feb 13, 1894, 359/853; 126/605; 126/684; 359/876 - DE 326516 Heliostat for astronomical purposes, Gustav Heyde G M B H, Sep 29, 1920,
333769 Heliostat, Alfred M. Mayer, Jan 5, 1886, 353/3 -

References

A Manual of Laboratory Astronomy, for use in introductory courses by Harlan True Stetson Phd, Eastern Science Supply Co, 1928 - but no mention of the heliostat.
Study, Measure, Experiment: Stories of Scientific Instruments at Dartmouth College by David Pantalony Richard Kreme & Francis Manasek 2005 - mentions a number of ESSCo instruments, but not this one.

Red Rock Solar Heliostats - Coelostat type 1 -

Instruments for Natural Philosophy - Optics - Heliostats

Links

PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale
Page Created 2016, June 29.

Fig 1 Top Overall View	Fig 2 Bottom View	Fig 3 Clockwork Marked: Waterbury Clock Co. Made in USA
Operation Photos
Fig 4 At first setup with hour angle pointer in night half of 24 hour clock, but it should be in the daylight half.	Fig 5 Rotating mirror flipped over and the central knob used to turn mirror 180 degrees, now you can see pointer is at about 10:00 while the house clock says about 11:30.	Fig 6 Closeup of heliostat showing time pointer.
	Fig 7 about an hour later The spot has moved but a little less than 15 degrees. Note you can see the pointer tip illuminated by the sun. But the pointer is not pointing exactly away from the sun, so the hour angle is not set properly. This demonstrates the interrelationship between the LMST and north azimuth. After 3 hours the spot has moved left and down a total distance of about 3 feet. The distance from the heliostat to the spot is about 36 feet. An angle of less than 5 deg. The sun moves 15 deg/hour so has moved 45 deg. Better initial alignment would reduce the spot movement.