. The Biological bulletin. Biology; Zoology; Marine biology. PENETRATION OF DAYLIGHT INTO THE SEA 319 attached to the post which, when moved to the left or to the right, opens or closes the leaves of the shutter. The lever arm is arranged as the armature of an electro-magnet (see Fig. 1). The free end of the lever arm, which is attached to the shutter, swings to the left or to the right according to whether the left-hand pole or the right-hand pole of the magnet is activated. Each pole is wound with 500 feet of double silk insulated No.' 30 copper wire. One side of each coil is grounded to the
. The Biological bulletin. Biology; Zoology; Marine biology. PENETRATION OF DAYLIGHT INTO THE SEA 319 attached to the post which, when moved to the left or to the right, opens or closes the leaves of the shutter. The lever arm is arranged as the armature of an electro-magnet (see Fig. 1). The free end of the lever arm, which is attached to the shutter, swings to the left or to the right according to whether the left-hand pole or the right-hand pole of the magnet is activated. Each pole is wound with 500 feet of double silk insulated No.' 30 copper wire. One side of each coil is grounded to the case (and hence through the sea water and support- ing steel cable to the hull of the ship). The operation of the shutter is controlled by a double throw switch conveniently located in the deck laboratory near the potentiometer. The ship's current is used to activate the coils of the electro-magnet (see Fig. 1). Closing the circuit momentarily suffices to open the shutter, or to close it. The shutter remains in the position in which it is left when the current is cut off. Since the current is allowed to flow for only a short interval, the coils may be greatly overloaded, â Jo Closed. Fig. 1. Diagram of the connections of the electrically operated shutter. (1) Position of switch to open shutter. (2) Position of switch to close shutter. Except for the moments of oper- ating the shutter, the switch is left with contacts broken in the vertical position. A, ammeter; ar, armature; &, c2, coils of electromagnet; f, 1-ampere fuses; p, post attached to leaves of shutter. thus increasing the strength of the magnet. Ordinarily ampere is sufficient to operate the shutter but the current may be increased to one ampere if necessary. This method has the additional advantage that no current is flowing through the electro-magnets while measurements in the photo-electric cell are being Please note that these images are extracted from scanned page images that may have been digita
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
