In praise of the humble Ro-Tap

January 25th, 2011

While we celebrate our new XRF and XRD equipment in Dr. Meagen Pollock’s petrology lab (which has already produced actual results), I thought we should also recognize our oldest piece of continuously-operated equipment in the department, the Ro-Tap Sieve Shaker:

This simple device was invented in the early 1900s by W.S. Tyler, and the company he founded still produces them today. The new versions are considerably sleeker than our massive machine. The Ro-Tap is designed to shake a series of nested sieves to sort granular materials into various size fractions. “Ro” refers to “rotate” and “Tap” to hammering at the top. You can imagine the noise that results. My Sedimentology & Stratigraphy class is using our ancient Ro-Tap (which was old when I was a student) to sort sediment samples. Each student was given a vial of an unknown sediment to describe by size distribution, mineralogy, grain shape and other characteristics. They will produce descriptive and statistical reports with conclusions about the possible environmental origins of the samples.

Joe Wilch preparing the sieve stack for the Ro-Tap.

The simple balance we use for weighing the size fractions, along with weighing trays and a datasheet.

Will Cary examining his unknown sediment sample with a photomicroscope. He is processing images through the computer on the right.

The beauty of science, especially Earth science, is that we blend the sophisticated and the simple as we describe and try to understand patterns in nature. You can stand in the basement of Scovel on some afternoons and hear the quiet purring of the X-Ray equipment as the steadfast old Ro-Tap bangs away in the background as it has for decades.

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