erture. This aper- pair of bolts are molded in the concrete with their ture preferably flares inwardly. Over the tube A is a heads bearing against a plate imbedded in the bot- casing B which is perforated to form a‘screen. Within tom of the tie and their threaded ends passing through the tube A is… … mounted in a suitable bore in the screw driver and at the lower end it carries a rounded centering head, the tip being cut away at this point to allow for the an enlarged body, as shown at A in the engravings. Fig. 1 shows a special construction for supporting an head. A recess is formed near the…
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