Lignum Vitae

An explosion rocked the humid night. Thrown to the deck, the young Confederate crewman escaped the projectiles flying everywhere. But not all hands were as lucky. Glancing into the boiler room, he found the first mate lying still. Was it a mortar shell that had felled him? It couldn't be; they were alone on the ocean.

The blow that struck the Confederate cruiser Georgia on that fateful evening in 1864 came from no enemy gunner. Instead, the awesome burst and devastating shrapnel was from shattering wood.

During the early days of oceangoing steamships, shipyards made many engine cogs and shafts of lignum vitae, an iron-tough wood so heavy it sinks in water. Unfortunately, crews found out that the wood also comes apart under extreme pressure when combined with more than 150° heat -- as was created in the engine room when the Georgia mate stoked the fire through the open boiler door.

Incidences such as this caused shipbuilders to abandon lignum vitae in machinery aboard surface vessels. However, because sea water naturally lubricates the wood, lignum vitae was adopted as the material for silent-running propeller shaft bearings in submarines and has only recently been displaced by space-age substances.

Above sea level, lignum vitae's remarkable hardness made it perfect for chopping blocks, block-and-tackle assemblies, and casters. Early woodworking tool manufacturers relied on the wood for mallets, plane soles, and bandsaw guide blocks. And, should you happen on a bowling ball from the 1800s, expect that it, too, will be rollable, rockhard lignum vitae.

Illustration: Jim Stevenson