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US patent number 1,281,096 was issued on October 8, 1918 to Christopher F Thullen of Chicago, Illinois, and assigned to Fed Ohde, Christopher F Thullen and August AF Dreyer. The three assignees are believed to have manufactured the On-The-Dot level, and sold it through the Chas. W Neimes Sales Company, also of Chicago, who advertised it as ‘a small instrument about three inches length that can be mortised into any board (picked up on the job) making a perfect level or plumb …bob…”. The picture and accompanying diagram show how it would have been used – essentially, hack a hole in a board, embed the O-T-D, and away you go!
Another, follow-up patent (no. 1,393,328) was issued on October 11, 1921 to “improve the construction of the level device shown in my prior Patent No. 1,281,096, so that the same may be made much stronger and lighter in weight, and at a greatly reduced price, and at the same time be more attractive in appearance and easier for assembling”
These turn up fairly regularly, and I have others, but what makes this one unique is that the four-fold paper describing its use and merits has remained with it for the nearly one hundred years since it was made. Such ephemera rarely survive – the paper is cheap, flimsy and acidic, and it effectively digests itself over time! What I find most interesting is the price – $1.50 in 1920 dollars is the equivalent of about $20 today! A carpenter’s wage at the time would have been around $1.10 per hour, or $14 today. If the same thing were made today, it would probably be plastic and sell for less than $10, while a carpenter would make about $20 per hour. So, the cost of the tool has halved in real terms, while the wage of the craftsman has increased by 50% in real terms.