Lawrence 8-A

Recently I saw an auction on eBay for a Lawrence slide rule that caught my eye — the slide rule somehow looked old and “different” than the old Lawrence model I was quite familiar with: the 8-B. So I bid on it, and won the auction for just a few dollars. When I received the slide rule, sure enough it was a new model (to me, at least): an 8-A. It is a very simple slide rule, with just four scales (A, B, C, and D). It has a rugged metal-framed plastic cursor, much nicer than later Lawrence models would have.

This particular example is in near-perfect condition except for one place (near 1.1 on the A scale) where it looks like a dog (or a kid!) bit down on the rule.

According to the indispensable International Slide Rule Museum (ISRM), Lawrence Engineering operated in Wabash, Indiana (printed on this slide rule) only from 1935 (the company’s beginning) to 1938, so presumably it was manufactured in this period. If the model numbers were assigned sequentially, as seems likely, then this model may have been the first, or one of the first, manufactured by the company.

To my surprise, when I started researching this slide rule I was unable to find out much about it. Mike Konshak at the IRSM had never heard of it. Peter Hopp lists it in his book, with a description that matches mine. I could not find any record of a sale of this model on eBay, though most of the Lawrence slide rules seem to be listed without any reference to model, so that’s not particularly meaningful. Has anyone else ever seen one of these?

The Fortress

The workers were off for the holiday on Thursday, but on Friday they were back. They first completed wiring up the rebar in the trenches (for the footings), and then put down a plastic vapor barrier under where the floor will be, covered that with a couple inches of sand, and then wired up a grid of rebar that will be inside the slab.

In the photo is a friend of ours (Jim Barnick) and Miki, our 9 month old field spaniel puppy.

At this point the work site is ready for the first pour of concrete, which will fill the trenches (forming the footing) and create the interior slab floor and exterior sidewalks (which will extend 2 feet around all four sides). Standing along side this work, my main reaction is to be amazed at the sheer quantity of steel in this job. The workmen seem fascinated by this as well, though for them the big surprise seems to be the requirement for 1/2 inch (about 1.2 cm) diameter rebar.

When the first pour has been made, all this work will be completely hidden. All that will remain of the iron work will be rows of vertical rebar that will mark the centers of the concrete block walls.

Before we can make this first pour of concrete, we have to have an inspector come out to approve the work so far. Hopefully that will happen by the middle of next week. Assuming we get approval, the fourteen cubic yards (about 14 cubic meters) of concrete required will be delivered in two truckloads. The trucks, which are very large, can only get to within about 200 feet of the building site — so a concrete pump will be used to move the concrete from the truck to the site.

This job will take three concrete pours all together. The first one I’ve already described. The second pour will come after the concrete block walls have been laid — that pour will fill the walls with concrete (as the blocks have vertical holes in them), and it will also create an angled top to support the gently sloping roof. The third pour will be for the roof — 10 inches (25 cm) thick, and extending outside the walls about 8 inches (20 cm).