There are, in history, several notable instances in which remote compasses are used. Lindbergh had an "earth inductor" compass which was a remote unit similar to the one in this thread, except as for power-source. (Lindbergh's had it's own wind-generated power.)
http://www.oldbeacon.com/beacon/earth_i ... ompass.htm
Ty Sundstrom, of the LIndbergh group had some interesting comments on the installation.
The original Earth Inductor Compass (EIC) installed in the Spirit was found to be defective while in San Diego.
A replacement was not available so it was left in the aircraft until being removed and replaced in New York. The replacement EIC was of a slightly different model as well,
which can be noted externally by the wind generator cups (looks just like a wind cup anemometer) on the later version
http://www.charleslindbergh.com/images2 ... _aug25.jpg
and the turbine style disc on the first (appears as a small round tuna can size disc on the top of the vertical mast on the back of the fuselage).
http://www.charleslindbergh.com/hall/1/ ... st1970.jpg
The magnetic compass (sometimes called a wet compass) was originally installed on the cockpit floorboard just to the left of the control stick torque tube in San Diego. You can see the original magnetic compass installation in this view;
http://www.charleslindbergh.com/hall/5/ ... st1970.jpg
The deviation create by the steel torque tube could not be compensated for because the torque tube would always be rotating slightly left and right as the ailerons were moved using the control stick.
Once the Spirit was in New York, the magnetic compass was replaced with a different unit as well.
It was relocated to a position directly in front of Lindbergh's head. The compass card which is the internal moving part of the compass which has the compass headings on it (north, east, south, and west) was printed backwards on the replacement compass which necessitated the use of a mirror on the instrument panel to actually read the compass. The compass installed apparently was not specifically made for the Spirit installation hence the reverse reading compass card.
Reverse reading compass cards were put in compasses which had remote installation locations which placed them well away from any substantial steel structure to improve the accuracy of the compass. Unfortunately, this also placed it sometimes out of direct view of the pilot so the compass was modified for this specific type of installation to read after being seen through a reflecting mirror.
The final installation of the magnetic compass can be seen in this view;
http://www.geocities.com/CapeCanaveral/ ... irinst.jpg
http://z.about.com/d/dc/1/5/W/3/WEB10067-2003h.jpg
It is interesting to note that Lindbergh had trouble with both the magnetic compass and the earth inductor compass at various times and once both failed him and he made the largest over water navigational error that was survived by anyone in a single engine aircraft when he flew out across the Caribbean at night when returning from South America on his good will tour there. The details of this adventure can be found in several places including Lindbergh’s log in the back of his book, the Spirit of St. Louis.
The work carried out on the instruments while in New York was done so by the Pioneer Instrument Company’s field rep. The instruments were originally bought from the Ryan Airlines Company but the earth inductor compass was purchased by Ryan from Pioneer Instrument Company. The special instruments installed in the Spirit were over and above the construction cost as seen in this invoice;
http://www.charleslindbergh.com/images2/Roberts8.JPG
There were many small changes to the Spirit while in New York;
The propeller spinner was replaced when the original was found to be cracked.
A carb air heater, duct hoses and cockpit control for carb air heater were installed.
The cockpit lights were disabled and their heavy telephone batteries removed.
Mirror was added to instrument panel to read replacement mirror.
The tailskid fairing was removed during skid repairs and not replaced.
One note; the removal of the heavy telephone batteries was never specifically addressed in any of the weight and balance computations by Donald Hall.
..........maybe we could all chip in and get him a laptop with a wireless data card .......we could call it and early birthday gift 
