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Frncis has made a great start. I think it is possible to get something looking 
even more like the original. 

Ronald van Riet gives the dimensions of the tubes in millimetres, but I think 
the original outside diameters would have been imperial sizes:
2 1/2 in; 2 5/16 in; and 2 1/8 in. Nowadays, the only stock imperial sizes 
that are near are 2 1/2 and 2 1/4 in.  There is a wide range of tube wall 
thicknesses, so it will be possible to get to the required dimensions by 
turning and/or boring.

The hexagonal top and the fluted base will be easy to make if a suitable material can be sourced.

I suggest we make a start with the simplest item, the Bygrave, and graduate to 
the more complex German instrument. I can obtain suitable aluminium tubing 
for only the two larger diameters - and only in 5 metre lengths. If someone 
out there can send me 10 inch lengths of tubing with the right inside and 
outside diameters to reach the required diameters, I would be happy to make a 
start and pass the results on to the "scale fitters". This could prove the 
concept as well as setting up a cooperative to supply those who don't own the 
necessary machine tools.

Bill Morris
Pukenui
New Zealand




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