This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
In addition to the shapes of bars shown in Figs. 145 to 148 inclusive, there is shown in Fig. 151 a plain bar without any condensation gutters, the joint being at A. B B represents the glass resting on the rabbets of the bar, while C shows another form of cap which covers the joint between the bar and glass. Fig. 152 gives another form of bar in which the condensation gutters and bar are formed from one piece of metal with a locked hidden seam at A. Fig. 153 shows a bar on which no putty is required when glazing. It will be noticed that it is bent from one piece of metal with the seam at A, the glass B B resting on the combination rabbets and gutters C C. D is the cap which is fastened by means of the cleat E. These cleats are cut about 1/2-inch wide from soft 14-oz copper, and riveted to the top of the bar at F; then a slot is cut into the cap I as shown from a to b in Fig. 154; then the cap is pressed firmly onto the glass and the cleat E turned down which holds the cap in position.
B, while the bars on each side of the sash to be raised are so constructed that a water-tight joint is obtained when closed. This is shown in Fig. 156, which is an enlarged section through A B in Fig. 155. Thus in Fig. 156, A A represents the two half bars with condensation gutters as shown, the locked seam taking place at B B. CC represent the two half bars for the raising sash with the caps D D attached to same, as shown, so that when the sash C C is closed, the caps
D D cover the joint between the glass E E and the stationary half bars. F F are the half caps soldered at a a to the bars C C which protect the joints between the glass H H and the bars C C.