Martha Smith, age 14, of Burlington, Vt., for her question:

WHAT IS A DAGUERREOTYPE?

A daguerreotype is one of the first forms of photographic print. It was named for its inventor, French painter Louis J.M. Daguerre. He made the first daguerreotype in 1839.

Daguerre made a polished, silvered, copper plate light sensitive by subjecting it to iodine fumes. He then exposed it from three to 30 minutes in a camera. He developed the image with mercury vapor and "fixed" it with sodium thiosulfate.

Improvements made in 1840 increased the sensitivity of the plate by bromine fuming, and enriched the image by toning it with gold chloride.

The highlights of. a  daguerreotype  are  whi t.ishy  The  sows  are bare, mirrorlike areas which appear dark when the plate is held to reflect a dark field. The permanency of the process and its ability to record minute details are its outstanding characteristics.

In the 1800s, Americans used daguerreotypes a great deal, especially for portraits.