_Dr. Diamond's Paper Processes._--We have been requested to call attention to, and to correct several errors of the press overlooked by us in DR. DIAMOND'S article, in the hurry of preparing our enlarged Number (No. 166.). The most important is in the account of the _exciting_ fluid,--the omission, at p. 21. col. 1. l. 47. (after directions to take one drachm of aceto-nitrate of silver), of the words "_one drachm of saturated solution of gallic acid_." The passage should run thus: "Of this solution take one drachm, and one drachm of saturated solution of gallic acid, and add to it two ounces and a half of distilled water."
In the same page, col. 2. l. 13., "solvent" should be "saturated;" and in the same article, _passim_, "hyposulphate" should be "hyposulphite," and "solari_s_e" should be "solari_z_e."
_Ancient Timber Town-halls._--Since my account of ancient town-halls (Vol. v., p. 470.) was written, one of these fabrics of the olden time noticed therein has ceased to exist, that of Kington, co. Hereford, it having been taken down early in November last, but for what reason I have not learned. Another, formerly standing in the small town of Church Stretton, in the co. of Salop, which was erected upon wooden pillars, and constructed entirely of timber, must have been a truly picturesque building, was taken down in September, 1840. A woodcut of the latter is now before me. Of the old market-house at Leominster I possess a very beautiful original drawing, done by Mr. Carter upwards of half a century ago.
_Magnetic Intensity_ (Vol. vi., p. 578.).--The magnetic intensity is greatest at the poles; the ratio may roughly be said to be 1.3, but more accurately 1 to 2.906. This is found by observation of the oscillations of a vertical or horizontal needle. A needle which made 245 oscillations in ten minutes at Paris, made only 211 at 7° 1' south lat. in Peru. The intensity and variations to which it is subject is strictly noted at all the magnetic observatories, and I believe the disturbances of intensity which sometimes occur have been found to be simultaneous by a comparison of observations at different latitudes.
For the fullest information on magnetic intensity, ADSUM is referred to Sabine's _Report on_ { 72} _Magnetic Intensity_, also Sabine's _Contributions to Terrestrial Magnetism_, 1843, No. V.