Although three centuries have elapsed since his death, the method of magnetizing iron first introduced by him is in common use to-day.
He made exhaustive experiments with a needle balanced on a pivot to see how many substances he could find which, like amber, on being rubbed affected the needle.

In this way he discovered that light substances were attracted by alum, mica, arsenic, sealing-wax, lac sulphur, slags, beryl, amethyst, rock-crystal, sapphire, jet, carbuncle, diamond, opal, Bristol stone, glass, glass of antimony, gum-mastic, hard resin, rock-salt, and, of course, amber.

He discovered also that atmospheric conditions affected the production of electricity, dryness being unfavorable and moisture favorable.
Galileo's estimate of this first electrician is the verdict of succeeding generations.

"I extremely admire and envy this author," he said.

"I think him worthy of the greatest praise for the many new and true observations which he has made, to the disgrace of so many vain and fabling authors." STUDIES OF LIGHT, HEAT, AND ATMOSPHERIC PRESSURE We have seen that Gilbert was by no means lacking in versatility, yet the investigations upon which his fame is founded were all pursued along one line, so that the father of magnetism may be considered one of the earliest of specialists in physical science.