How did cricket fielding positions get their names?

'Off-side' and 'leg-side' were coined in the 1800s, when travel was done through carriages, with off-side being the one from where a rider would mount the carriage. 'Slip' position was named so that the fielder could take advantage of any 'slip' by the batsman, while 'silly point' was named because it was 'silly' to stand so close to the batsman.