MESSRS. EDITORS—In the number of the SCIENTIFIC AMERICAN dated the 13th inst., you state, in answer to a correspondent, that gold pens cannot be re-pointed ; and you give as a reason, that in soldering on the point, the elasticity of the gold is destroyed by the heat. Hitherto this has been the case, but by recent discoveries and a series of experiments, I have surmounted all difficulties in re-pointing gold pens. It is true that heat destroys the elasticity of the gold, but I put on the point, reproduce the elasticity, and make the pen equal to new at a trifling expense. L. H. MARTIN. New York, February, 1858. [We have seen the fruits of our correspondent's discovery, in a re-pointed gold pen, which, in every respect, is as good as when first made. The discovery is a very useful one indeed, as the gold pen business is now a considerable institution in our country.—EDS.