Okay, here is all the info I gathered from the book. All quotes in italics
below are from "Boxwood & Ivory" mentioned earlier.
Summary: Ctb is right. the No. 38 was only offered in ivory with nickel
silver trim. So a $200 to $400 estimate applies. Just don't clean it or
"restore" it! Second, I've seen these sell for a little as $40 and had always
assumed those to be boxwood. So now I'm kicking myself for not grabbing
them up when I could. Oh well.
"No. 38 Carpenters Caliper Rule, 6 Inch, 2 Fold
Offered: 1855 thru 1922
Construction: Square Joint, Left Hand Caliper
Leather Case (1912 thru 1917)
Material: Ivory; German Silver Hinge, Caliper, & Tips
Width: 1/2 Inch
Graduations:
Body: 8ths and 16ths of Inches (1872 and before)
8ths, 10ths, and 16ths of Inches (1874 thru 1877)
8ths, 10ths, 12ths, and 16ths of Inches (1879 and after)
Caliper: 16ths of Inches
Between 1888 (Ref. 14) and 1892 (Ref. 15) the caliper jaw on this rule
was changed slightly, to have a rounded back (Fig. 102b) instead of the
hollow back (Fig. 102a) which had been customary. No obvious reason
can be found for this change; it must have been made for merely cosmetic
purposes, or possibly to slightly reduce manufacturing cost (the hollow
would have had to be milled, but the rounded back could be satisfactorily
shaped by hand on a grinding disk)."
Here are some other facts related to your rule. These quotes are
from various random places in the book..
"It was also in about 1918-1920 that Stanley ceased production of
ivory rules. The cost of making these premium rules had been rising
rapidly ever since the turn of the century, driven by higher labor costs
(there was more hand work in an ivory rule than in an equivalent
boxwood one) and an increasing scarcity of elephant ivory."
"1922 was the last year that ivory rules were offered; by 1925 the eight
which had managed to survive World War I (the Nos. 38, 39, 40, 40V,
86, 87, 88, and 92) had all been removed from the catalogue, and
Stanley was no longer a maker of ivory rules."
"It is not known whether the ivory rules offered after the war were
newly manufactured, or just existing stocks which were being sold
out. It is significant to note that there are no known examples of any
of these rules bearing the Sweetheart trademark. If they had still
been in production in 1922, surely some would be found marked with
the new trademark introduced in that year."
"Three types of metal were employed in the manufacture of the
Stanley rules. Brass was the most common, but German (nickel)
silver was usually used in its place on ivory rules and steel, of course,
was used where high strength or wear resistance was required (for
joint pivot pins and assembly pins, for instance)."
And most interesting of all, I always wondered if nickel silver actually
contains silver. It's really just a type of brass...
"German silver is a white alloy of copper, zinc, and nickel which
was frequently used for the trimmings on premium-quality rules, due
to its fine silver-like appearance, and its improved durability. This alloy
originated in China, where its composition is said to have been known
since time immemorial, but was only introduced to the English-speaking
world in 1830, when a sample was brought to England from Germany
(hence its name). For many years the alloy was very widely used for
electroplated tableware and for scientific instruments, and only recently
has it been largely replaced in these applications by other materials.
German silver (also known as nickel silver, Chinese white silver,
Packfong, Electrum, etc.) is basically a modification of the alloy for
brass, containing about 60 percent copper, 20 percent zinc, and 20
percent nickel. It has all of the workability characteristics of brass, and
can be cast, rolled, and drawn. At the same time, it possesses the
properties of being hard, tough, and not easily corroded. When polished
it very closely resembles real silver, being only slightly more gray than
that metal, and tarnishing to a light yellow, instead of an orange-black.
This alloy was used by Stanley (and most other rule makers) to trim
its ivory rules, just as brass was used with the wood ones. There were
some exceptions, of course; some of the smaller ivory rules were initially
offered with a choice of brass or German silver trim, and a few of the least
expensive in brass only, but generally speaking the rule was brass for
wood, German silver for ivory."
