it is good

GOOD: Place the end of the palm against the mouth; then bring it down against the open left hand so that the back of the right hand rests in the palm of the left. In common use the latter part of the sign is omitted and the hand is simply thrown forward from the mouth.

because

BECAUSE: Place the end of the forefinger of the right “L” hand at the forehead, above the right eye; draw the hand away to the side, assuming the position of “A,” and then raise the hand on a level with the top of the head. The hand is sometimes given a peculiar twisting motion.

since

SINCE: Place the forefingers of the “G” hands above the right shoulder, end to end, but not touching; giving each a turn so the ends describe circles opposite each other, bring them both forward to the front.

night

NIGHT: Left horizontal prone forearm pointing out to the right, right vertical forearm lowered over the left. (If lowered to horizontal it would signify “Evening” if not so low, it would indicate “Afternoon” if lowered below horizontal, it would denote “Night”).

to leave (a place)

LEAVE, RETIRE, WITHDRAW ONESELF: Extend open hands, palms down, out toward the left side, one farther toward the left than the other, somewhat “tandem;” draw them back toward the right side of the body and a little up, bending the fingers down from the knuckles.