The Gravestone Data Level part of this project requires you to use a set of micrometer calipers. If you want to measure marble gravestones without lead lettering, the calipers only need to be able to measure thickness. If you want to measure gravestones WITH lead lettering, the calipers will need to be able to measure thickness and depth. Calipers that can measure depth are easy to recognise as they have a rod that slides out when you slide the calipers apart.
Calipers that do this come in many different types - slide calipers (sometimes called vernier calipers), dial and electronic calipers.
Electonic Calipers (with depth rod)
Dial Calipers (with Depth Rod)
The most common and cheapest is a slide caliper that has a depth rod. They can be made of metal (most expensive) or plastic (least expensive). Also, you need a micrometer that reads in metric (mm).
Basic metal vernier caliper micrometer (with depth rod)
All of these types of calipers can be found for sale at hardware stores. Suitable calipers for this project are also available from the EarthTrek online store.
How to read the scale on a slide caliper
Reading the scale is not complicated. The bottom row of numbers has a zero mark. To find the number of millimeters, just count the number of full marks that occur above and the to left of the zero mark. To find out the number of tenths of millimeters, just run your eye along the bottom scale marks until a bottom make aligns perfectly with a mark directly above it. The number of tenths is the number written below the mark on the bottom scale.
How to read a caliper micrometer. Image - Joaquim Alves Gaspar
In the example below, the scale reads 5.5 mm
In the example below, the scale reads 1.75 mm.
If you have a dial or electronic calipers, follow the instructions that came with the device on how to set and read the scale acurately in millimeters.
How to use the calipers in this project
To use these caliper micrometers in this project is quite simple. Following the protocols on how to select a gravestone for measuring and where to measure, follow these simple gudelines on how to get accurate measurements.
For Thickness of Gravestones
Open the calipers so they are wider than the gravestone you are measuring and place the calipers around the gravetsone. Slide the calipers together so they touch the gravestone on both jaws (see image).
While the calipers are in place (do not remove them as you might change the reading), read the scale carefully.
For measuring the distance from marble to lead letters
Take your micrometer and side it so that the depth rod is about 10 mm long. Then place the end of the rod against the marble very close to a lead letter. Slowly slide the micrometer so that the end of the slide is against the lead. Do not push too hard as lead is soft. You want to just touch the lead and not indent the lead. Pull the micrometer away so you can read the scale.
