62. This Contractor shall furnish and install tho complete mechanism for opening and closing the covers over the cyclorama light trough.
63. The covers shall be operated in three separate groups, as indicated. For each group there shall be provided an electric motor, and a suitable train of quiet reduction gearing, driving a line shaft, supported on roller bearing pillow blocks. To the line shaft there shall be attached cast steel arms, the ends of which shall be attached to the covers by means of sliding connections. The arms shall be counterweighted to balance the weight of the covers.
64. The motion of the covers shall be controlled from a push-button operating station, installed on the stage as directed, and automatic stops shall be effected by means of geared limit switches. This Contractor shall furnish and install all machinery, motors and control apparatus.