The Author's View and Mine

How a Canal Lock Works

A canal cannot run uphill. Where the land rises, engineers build a lock: a chamber with a gate at each end. A boat going uphill enters the lock through the lower gate. The gate closes behind it. Sluices in the upper gate are opened. Water flows in from the higher stretch of canal, and the boat rises with it. No pump is needed, because the water comes down by gravity. When the water inside matches the level above, the upper gate can be opened and the boat moves on. Going downhill, everything runs the other way: the water is let out, and the boat sinks with it.

How Braille Was Invented

Louis Braille was blinded in an accident at the age of three. At his school, blind pupils read by tracing raised letters pressed into paper. It worked, slowly — a fingertip cannot take in a whole letter shape at once — and nobody could write that way at all. When Braille was twelve, a soldier visited the school with a code of raised dots that soldiers used to read messages in the dark. It was too complicated, but the idea of dots was right. Braille spent three years simplifying it. He settled on a cell of six dots, small enough to sit under one fingertip. He was fifteen when he finished. He was forty-three when he died, and the system was not widely accepted until after that.