Having occasion, some little time since, for an assay balance, and being well aware of the points wherein those in use here are deficient, I applied myself to the task of so arranging existing materials, as to produce, if I could, a more effective instrument. The first is very little more than an exceedingly delicate pair of ordinary scales; in fact, a very light scale-maker's beam, adjusted, as they are accustomed to do, by carefully " setting" it, so as to obtain correct length of arm, and

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... aight line of fulcrum and points of suspension. The second is an instrument imported from France, or better, made here upon the French plan. Of these, tbc French are but an improvement upon thc first class; the hcams (of almost all) being permanently adjusted whcii finished. Thosc, however> ma& by Two forms of assay balances are most common in England.