Acts 3:1 - Wesley's Explanatory Notes

The ninth hour — The Jews divided the time from sunrise to sunset into twelve hours; which were consequently of unequal length at different times of the year, as the days were longer or shorter. The third hour therefore was nine in the morning; the ninth, three in the afternoon; but not exactly. For the third hour was the middle space between sunrise and noon; which, if the sun rose at five, (the earliest hour of its rising in that climate,) was half an hour after eight: if at seven (the latest hour of its rising there) was half an hour after nine. The chief hours of prayer were the third and ninth; at which seasons the morning and evening sacrifices were offered, and incense (a kind of emblem representing prayer) burnt on the golden altar.