All objects are made of one or more materials, and the selection of these materials is never left to chance. Although choice may be limited by cost, time and place, someone carefully selects the specific materials used in a particular object. By identifying these materials and thinking about their qualities (strength, weight, etc.), a curator can better understand the nature and function of any object.

What am I made of? Telegraph Insulator, ca 1876 (CSTM 740026) See: Connexions

This simple-looking artifact is a glass telegraph insulator. Produced in large numbers, insulators like this one played a very important part in the development of telegraph networks.

Telegraphy uses electrical pulses, following an established code, like Morse code, to convey information. To carry an electrical signal a long distance required wires strung on poles. These poles were usually made of wood. But the wires could not be attached directly to the poles, because when the poles got wet they would draw away some, or all, of the electrical pulses. This would stop, or seriously reduce the strength of, the signal being sent. Something had to be placed between the wire and the poles that would preserve, or insulate, the signal, hence the name “insulator.”

The choice of material for insulators is therefore very important. In this case, glass was chosen because, as a material, it is an excellent electrical insulator: it does not conduct or carry an electrical current, and it does not absorb water. Glass is also relatively inexpensive and it can be heated into a liquid and poured into moulds. This made it easy to mass-produce insulators of the same quality, size and shape.