Capturing Fish Measurements and Counts with Calipers and Probe Interfaced with a Computer or Pocket Calculator

Dial calipers and a counting probe were interfaced to a Hewlett–Packard 9845 minicomputer. Data input into computer memory can be output on the computer display screen or the computer printer, or stored on tape. A comparison of automatic and manual dial calipers showed that measuring, recording, and magnetic tape storage of data was twice as fast with the automatic system; measurements made on a hard object were less precise with manual as with the automatic calipers; but 95% of the repeated automatic measurements on the same object were within ±0.2 mm. Intercaliper differences between the four calipers studied exceed 0.1 mm with the same operater. Other sources of variation such as pressure of caliper jaws on measured parts, inter-caliper differences, and inter-scientist technique, probably exceed the error introduced by automation. Automatic measuring avoids mis-writing, -reading, and -keying the values into the computer. We conclude that automatic measurement offers benefits to museum taxonomy, other s...