is moved, as they are backed by springs that press them at all times against the columns.

When the deck is at its lowest position it will he held firmly to the piers, with a proper provision for longitudinal expansion, in such a manner as to relieve entirely the guide-rollers from carrying the wind-pressure, so that they can act only when the deck is raised.

The machinery-house will be about twenty-two feet square and fourteen feet high under the eaves, capped by a dome, and finished in an ornamental style. The floor is to be of I beams supporting a four-inch plank floor.

All main sheaves are to be covered with ornamental housings, and all gears are to be covered with small galvanized-iron hinged housings.

The velocity of the lifting deck will be limited to one foot per second by means of an automatic governor attached to the electrical machinery. The time required to either raise or lower the deck the full height will therefore be about one minute.

To provide for a possible breakdown of the electrical machinery, a man-power apparatus will be employed, consisting of two capstans connected to the main shaft by means of gearing located in the machinery-house, and operated by levers working in horizontal planes. The moving deck and counterweights will be balanced when the deck is at mid-height. On this account there will be a constant tendency to hold the deck from vertical motion at both ends of its travel, because of the unbalanced weight of the wire cables. In one sense this will be a decided advantage, but it will necessitate extra power to start the mass in motion. Again, the deck will be balanced for ordinary conditions of weather, but it is probable that the weight will be increased by moisture, accumulated dirt, etc. This, if it exist to a moderate extent, will be an advantage, in that it will tend to hold down the deck on the piers; but, as  before,  it  will  require  increased  power  to  start  motion  and  to operate.  However,  the  amount  of  power  available  will  be  large  enough to  meet  all  conditions  of loading and  contingencies.   Should