D Some Collection Statistics

Total number of slide rules: 294.

Range of rule ages: 49 to 214 years. Average rule age: 81.1 years.

Number of rules at least 75 years old: 156. Number of rules at least 100 years old: 62.

Number of rules at least 125 years old: 11. Number of rules at least 150 years old: 5.

Countries of the Slide Rule Makers

Country	No. Rules	Makers
CHN	2	Ruyi, UIF Shanghai
DEN	2	Rietz
EGER	1	Reiss
FRA	2	MARC
GER	37	Aristo, Dennert & Pape, Dietzgen, Faber, Faber-Castell, HH, KHH, Kolesch, Nestler, Staedtler
JPN	42	Alco, Concise, Hemmi, Relay-Ricoh, noID
UK	19	Blundell Rules Limited, Davies, Dring and Fage, E.S.A. London, Fearns Calculators, Fowler, Jacob and Halse, Otis King, Sikes, Stanley, Thornton, Unique, noID
USA	187	Acu-Rule, American Blueprint, Baetzmann, Boykin, C-Thru, Charvoz-Roos, Dietzgen, Engineering Instruments, Felsenthal, Festus, Gilson, Goodyear, J.B. Carroll, K&E, Kahl Scientific, Lawrence, Novotni, P.A.S. Co., Palmer, Pickett, Richardson, Sandish, Sillcocks-Miller, Sterling, noID
USSR	2	Factory10, MATSKU

Primary Construction Materials

Material	No. Rules	Makers
Al	32	Gilson, Pickett, Reiss, Richardson
bb	35	Hemmi, Relay-Ricoh
iv	1	Jacob and Halse
Mg	7	Acu-Rule, Pickett
pl	66	Acu-Rule, Aristo, Blundell Rules Limited, Boykin, C-Thru, Concise, Dietzgen, Faber-Castell, Fearns Calculators, Felsenthal, J.B. Carroll, K&E, Kahl Scientific, MARC, Novotni, Pickett, Rietz, Ruyi, Sillcocks-Miller, Staedtler, Sterling, Thornton, noID
pp	3	Goodyear, Palmer
ss	10	Alco, Fowler, MATSKU, Otis King, P.A.S. Co., Richardson
wd	140	Acu-Rule, American Blueprint, Baetzmann, Charvoz-Roos, Davies, Dennert & Pape, Dietzgen, Dring and Fage, E.S.A. London, Engineering Instruments, Faber, Faber-Castell, Factory10, Festus, HH, Hemmi, K&E, KHH, Kolesch, Lawrence, Nestler, Pickett, Richardson, Sandish, Sikes, Stanley, Thornton, UIF Shanghai, Unique, noID

• Key: wd (wood), bb (bamboo), pl (plastic), ss (stainless/steel alloy), Al (Aluminum), Mg (Magnesium), iv (ivory), pp (paper)