Pranksters purloined the second Wursthaus balloon in less than a month early Saturday evening, but they won't get a chance to have a go at a third one.

Co-manager of the local delicatessen Jack Spear said last night that his establishment will not fly another aerial welcome mat unless one of the two stolen is returned. However, he has posted another reward of $50 in hopes that the thieves will bring at least one balloon back.

Cambridge police hypothesized that the same people, presumably Harvard students, who took the first balloon, returned again for the second Saturday night, since both were removed in the same way.

Fastened to Roof

The balloons were fastened to the roof of the delicatessen by 150 feet of rope. The roof of the building is accessible by a flight of steps from an alley off Boylston street.

The thieves apparently ascended to the roof by the stairs around 5:30 p.m. Saturday, hauled in the eight foot structure, deflated it, and walked off. A student reported seeing a group of men carrying it down Massachusetts Avenue around dinner time.

The balloon taken this weekend had only been in the air two days before its theft. Like the one stolen after the Columbia game, it had the name of the delicatessen painted on its side.