There are five screws / knobs you need to use. Ignoring any of the small vertical ones, there are five horizontal knurled screws/knobs, four on the left and one on the right. The top one, "A" is a set screw which, when loosened, allows the top platform to which the spring attaches to move freely. The next one is the large knob on the left, "B"; this is a geared knob that moves the whole top section of the balance vertically when turned. The third screw, "C", is a set screw that keeps immobile the platform to which the alignment mirror is attached. The fourth screw, "D" holds the beaker platform in place. Finally, the screw on the bottom-right, "E", is a set screw that keeps the marked scale tight.
- Set up the instrument.
- Select a spring of appropriate strength for the weight of the specimen you wish to test.
- Screw A should be loose, B should be turned so that the top assembly is as low as it goes, C and D should be tight, and E should be loose. The scale should read zero on both sides.
- The spring should be attached to the top platform, then the black wire with the leveling disk is attached, and finally the double-pan assembly is attached to the hook at the bottom of the wire.
- Be sure screw A is loose. Holding knob B tight, raise the top platform (that the top of the spring is attached to) until the leveling disk is near the line in the mirror. Tighten screw A.
- Adjust the platform that the beaker sits on (loosen screw D) and the water level in the beaker so that the bottom pan is submerged along with most of the wires that attach it to the top pan, and the top pan is dry (it should not touch the water at any time).
- Adjust the mirror platform (loosen screw C) so that the line is a bit above the reference disk on the black wire.
- Level the instrument by adjusting the two screws on the rear support legs so that the black wire goes through the middle of the hole in the mirror platform.
- Zero the instrument
- Loosen screw A. Holding knob B tight, raise the top platform slowly until the leveling disk is exactly aligned with the line in the mirror. Tighten screw A. (You can perform fine adjustment of the mirror with the small vertical screw on its top).
- Note that now the spring is extended without any sample, the disk is at the line, and the scale reads zero on both sides. Any extension due to the weight of the sample can now be read, with zero as the pre-sample reference. Good!