http://www.celticknot.com/content/view/40/42/
DETERMINING ANVIL WEIGHT
Older anvils are marked with a three digit number. Anvils were weighed according to the British system of measurement. The first digit indicated the number of whole hundredweight's, the second indicated the number of quarter hundredweight's and the last number indicated the number of pounds remaining. A hundredweight (abbreviated cwt.) is actually 112 pounds. A quarter cwt. is twenty eight pounds.
To calculate the weight of the anvil in pounds: multiply the first number by 112, multiply the second by 28, and add the two results to the third number. A 1-2-6 anvil is 174 lb. ((1x112)+(2x28)+6=174).
http://www.metalartistforum.com/forum/showthread.php?tid=2840
Before 1850 PW's had a "colonial" style shape (more squat than the classic pattern) From 1850 to 1860 there was no circle of words saying "Solid Wrought", it just said it in a straight line. After that in a circle. Up until 1885 anvils over 150# had a 2 piece steel face instead of a 1 piece, forge weld line would be visible on the face. After that one piece face all weights. After 1910 they added "England" under the name per English law. After 1930 (Postman thinks) they went to a 2 piece construction like Hay Buddens with the whole top half of steel, not just a face lamination. Hope this helps. BTW I understand he's working on a 2nd edition.
http://www.abana.org/resources/discus/messages/273/2118.html?1191500177
I have read in several places the law actually went into effect in 1891 or 92. In Anvils in America Richard Postman seems to give 1910 as the year PW started stamping ENGLAND on their anvils. Which is correct I don't know.
The earliest PWs were of the multiple piece build-up technique until about 1852, when they started the two-piece plus top plate technique. Those are just marked as P. WRIGHT WARRANTED (with the warranted meaning the anvil body was wrought iron). From 1852-1860 there was a noticeable seam between the top and base and they were stamped as just PETER WRIGHT PATENT. After 1860 they seam pretty well disappeared and they started using the SOLID WROUGHT in a circle stamp - typically around the middle stone weight number. Solid wrought also meant the anvil body was of wrought iron. Some changes, such as the shape of the horn,
were made after 1860, but essentially the basic design stayed the same until they were bought out in the 1930s by Nash.
One aspect of it being a late model PW is sometime after 1900 they stopped putting SOLID WROUGHT in a circle in their logo. I suspect they started to use at least mild steel bases so you can be pretty sure one without that stamping is a late production.
Yes, all PW were manufactured in Dudley, although Peter Wright himself may have worked at Mousehole Forge earlier. In a discussion with Mr. Postman he indicated apparently PW was the largest production facility in Dudley (itself a manufacturing city) from about 1830 to the 1930s - about 100 years. However, he
has been able to find out virtually nothing about them besides a rendering of the plant.
Richard Postman also told me that prior to the U.S. Civil War Mousehole Forge dominated the English export market. After the war Peter Wright was the major anvil brand sold until the late 1800s when several U.S. manufacturers starting making similar anvils. (They remained the leading British exporter, but their
export numbers fell off due to the competition.)
My theory on why people preferred PWs over MHs is PW now had a sleak body while MHs remained somewhat blocky until the late 1800s. In fact, the "London-pattern" designation was based on the PW two-piece bodies anvil.)
(Prior to the Civil War Mousehole Forge's main export competitor seems to be William Foster, and then Wilkinson, based solely on the number which show up on eBay. Some Hill (Burmingham) have appeared, but mostly just south of the Canadian border. This may indicate they were exported to Canada and some found their way south. Other brands also show up from time to time.)
He suspect PWs are the most commonly found anvils in the U.S. today.
The book, Anvils in America, is available directly from the author for $70 for Media Mail or $75 for Priority Mail. Autographed upon request. Address: Richard Postman, 230 Fisher Court, Berrien Springs, MI 49103.