Introduction: Ancient Egyptian Combination Square and Level
The photo shows a combination square and level from the time of Pharaoh Ramses (about 2,000 years B.C.). I could not get to the exhibit, so I bought a glossy photo book, and this page was in the book. The level is a plumb line with a mark on the crossmember of the square. I always wanted to build one of these.
Step 1: Rip Three Pieces
Wood always moves with changes in humidity. Egypt is a very dry climate, so precision instruments from wood might work there. I made my Egyptian square and level from 1/2 inch plywood because it will not shift with changes in humidity.
I ripped three pieces 2 1/4 inches wide. I made the legs of my square 20 inches long each. The original in the museum exhibit has legs about 14 1/2 inches long.
Step 2: Rough Layout of the Pieces
It would be possible to build this without the use of a modern square, but I will use one in this step to speed things along. The crossmember will need to be cut to length. Pieces will need to be marked for dado operations to prepare for making lap joints that will be strong after gluing. The crossmember is 2 1/4 inches above the bottom ends of the square's legs. The ends of the square legs need to be cut at 45 degrees so they rest flat on the work surface. If I were to do it again, I would change the crossmember to be more like 4 inches above the work surface along the lines of the original from the museum exhibition. See the photo in the Introduction.
Step 3: Fit the Pieces for Gluing
Fitting the pieces after cutting them to length and making dado cuts for lap joints should be straightforward, but there can be fitting problems. Make whatever corrections are necessary for a good fit. Glue the pieces at the lap joints.
Step 4: Adjust While the Glue Is Fresh
The two legs need to form an exact 90 degree corner. I have glued and clamped the joints, but the glue is still wet, so some adjustments can be made.
It was in the elementary grades that I learned about the 5, 4, 3 trick for making a triangle in which one corner is exactly 90 degrees. If I remember correctly, we were told the Egyptians discovered this handy piece of knowledge. It is entirely likely the square/level combination in the Ramses exhibit was made by using the 5, 4, 3 trick.
I measured from the right angle corner down one leg 16 inches (4 x 4 inches) and down the other leg 12 inches (3 x 4 inches). I marked both measurements by scoring the wood with a knife, which is much more precise than a pencil mark. The hypotenuse or distance between these two marks needs to be adjusted until it reads exactly 20 inches (5 x 4 inches). Then clamp the joints firmly and check the three measurements again before the glue sets up.
The ancient Egyptians had wood glue. They made it from milk curds and a few other things, as have others through history. It is called casein glue.
Step 5: Trim Ends at the Joints
The sides of the square's legs need to be straight and smooth. In the photo you see that the crossmember extends beyond the surface of one of the square's legs. Remove the part that extends with a file, a chisel, or a power sander. Do not cut into the leg of the square.
Step 6: The Plumb Bob
The string from which the plumb bob hangs does all of the work. The point on the plumb bob is purely decorative during use of this project as a level.
This is the tip of a heavy steel stake about 10 inches long that I found on the road while I was out riding my bicycle one day. I always try to bring odd pieces of steel I find home for later use in my projects. I used an angle head grinder with a cutting wheel to cut and form this plumb bob. I ground away rough edges and drilled a small hole for a piece of string.
Step 7: Fish Line
I used 30 pound test nylon fishing line in place of string to hang the plumb bob. I did not want the knots to loosen, so I coated them with a bead of hot glue. The line should be long enough that the plumb bob does not hang up on the crossmember, but short enough that the plumb bob does not drag on the work surface.
Step 8: Calibrate the Level
In the mid-1970s an author sold many, many books by claiming the Egyptians would have needed help from outer space to build the pyramids all to the same grade level. The Public Broadcasting System program NOVA challenged his assertion by mentioning that if you are Egypt, you can muster enough slave labor to build dikes and flood a large area. Use poles set in the ground to mark the water level wherever needed. Then drain the water and have the slaves remove the dikes.
I placed masking tape on the side of our bathtub. I ran a couple of inches of water into the tub and marked the water level on the tape. I drained the water from the tub. Next I aligned the ends of the square's legs with the marks. When the plumb line came to rest, I made a mark on the crossmember of the square/level. When the fish line is over that mark, the surface on which the square/level rests is level.
Step 9: Something Modern
I made a marker from a piece of thin aluminum and made it adjustable, just to be safe. I used a sharp tool to scribe a line that can be seen from the front or by looking down on the crossmember from above. I darkened it by running my gel ink pen over the scribed line. Otherwise, it is what you see.
Step 10: In Use
Using the square is like using any other square. Hold the plumb bob in one hand and grasp the crossmember.
Using the level function is easy if you can hold the ends of the square's legs with one hand on each. Allow the top of the square (the 90 degree corner) to tip toward yourself so the plumb line can move freely, but still vertical enough that the plumb line is close enough to the crossmember for a good indication of how the plumb line aligns with the scribed line on the aluminum.
Just because someone lived 4,000 years ago and did not have some of the tools we know does not mean they were without ways to get the same job done in a very precise manner. I look forward to using this square and level to build something one day soon. Everything about it looks to be very accurate. And, it was constructed in much the same way ancient Egyptians would have done the job.