81.   They began giving formal tours a few months ago.

82.   They give the tour of the four-story brownstone, including their own five-bedroom, two-bath triplex with stained glass windows on every floor.

83.   They have converted the building into the small factory that constructs the instruments and gives tours.

84.   This was underscored when David Bull, chairman of paintings conservation at the National Gallery, gave a visitor a tour of the Vermeers he had recently finished cleaning.

85.   To illustrate, Watson gave a tour of the Upper West Side apartment that he has turned into his office and showrooms.

86.   Today, the operators give tours of the once-secret cellar, whose carefully balanced door is opened when a stiff wire is inserted in a small hole.

87.   Tours are given during the day, and at night the space is given to an eclectic selection of reasonably priced art-house films, plays and concerts.

88.   Tours are given several times a day by knowledgeable park rangers or volunteers.

89.   Tours are given twice daily.

90.   Tuesday, in the primeval ooze, I was given a tour.