Persia, accident to, [274]
Pisa, tower of, [104]
Pitchers, why they have lips, [89]
Pneumatics, what it teaches, [146]
Pneumatic trough, [167]
Pop-guns, [164]
Pottery, centrifugal force used in, [216]
Powder, explosive force of, [165]
Prince Rupert's drops, [33]