barometers, however suspended, would stand, without the slightest injury, the most severe concussion that they would ever be likely to experience in any sea-going man-of-war." These trials were conducted under the superintendence of Captain Hewlett, C.B., and the guns were fired in the course of his _usual_ instructions. His reports to Admiral FitzRoy, giving all the particulars of the trials, are published in the "Ninth Number of Meteorological Papers," issued by the Board of Trade.[2] 25. NEGRETTI AND ZAMBRA'S FARMER'S BAROMETER AND DOMESTIC WEATHER-GLASS. It is a well-known fact that the barometer is as much, or even more affected by a change of wind as it is by rain; and the objection raised against a simple barometer reading, as leaving the observer in doubt whether to expect wind or rain, is removed by the addition of the Hygrometer, an instrument indicating the comparative degree of dryness or dampness of the air;--a most important item in the determination of the coming weather. The farmer should not be content to let his crops lie at the mercy, so to speak, of the weather, when he has within his command instruments which may be the means of preventing damage to, and in cases total loss of, his crops. The farmer hitherto has had to depend for his prognostication of the weather on his own unassisted "Weather Wisdom;" and it is perfectly marvellous how expert he has become in its use. Science now steps in, not to ignore this experience, but on the contrary, to give it most valuable assistance by extending it, and enabling it to predict, with an accuracy hitherto unknown, the various changes that take place in this most variable of climates. To the invalid, the importance of predicting with tolerable accuracy the changes that are likely to occur in the weather, cannot be over-rated. Many colds would be prevented, if we could know that the morning so balmy and bright, would subside into a cold and cheerless afternoon. Even to the robust, much inconvenience may be prevented by a due respect to the indications of the hygrometer and the barometer, and the delicate in health will do well to regard its warnings. [Illustration: Fig. 17.]