Abstract: Hydroelectric power generating station which, in one embodiment, includes a main tunnel that crosses beneath a river upstream from a waterfall, a plurality of branch tunnels that intersect the main tunnel and open through the face of the earth behind the waterfall, water wheels which are mounted in the branch tunnels, extend into the waterfall, and are driven by the falling water, and electrical generators which are mounted in the tunnels and driven by the water wheels. In other embodiments, water for driving the water wheels or turbines is taken from the river above the tunnels or from the upper part of the waterfall and is returned to the river toward the bottom of the waterfall.

Abstract: Power operated caulking gun having a housing, a cradle extending from the housing for receiving a cartridge of fluent material, a push rod for engagement with a cartridge in the cradle for dispensing the fluent material from the cartridge, a drive shaft extending from the housing and adapted to be received in the chuck of a drive tool, drive means interconnecting the drive shaft and the push rod, and a stabilizer extending from the housing for engagement with an abutment on the barrel of the drive tool to prevent rotation of the caulking gun relative to the drive tool. In some embodiments, the cradle is adapted to hold a cartridge having two tubes of fluent material positioned side-by-side, and the caulking gun includes a second push rod for dispensing material from the second tube in the cartridge.