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Fig. 5. I. baseplate; 2. upper plate; 10. cylinder; 11. plunger;
12. husk of leather for good closure of the plunger; 13. axis of the
plunger; 14. little ring of felt to catch the oil; 15. nut to fasten the
axis of the plunger on the upper plate; 16. stud for right register of
the upper plate; 17. hole to catch the register stud No. 16; 18. ring
to stop the plunger in upper position; 19. plunger in undermost
position; 20. shell to close the cylinder; 21. conduit for pressure.
The accuracy obtained with this instrument is controlled with
each contact printing and it is evident that combining sheets only
by putting them on four studs on the glass plate in the dark room
gives a great improvement and an important saving in time.
The apparatus and the glass plates with studs have been con
structed in the workshop of the Dutch Topographic Service.
The total cost does not exceed 600.
