[132] +The question+: In the upper Gallery of the Dome of St. Peter’s Church at Rome, and 50 Feet below the Top of the Cross, the Barometer, from a Mean of several Observations, stood at Inches 29.5218 Tenths: the attached Thermometer being at Degrees 56.6 Tenths; and the Air-Thermometer at 57 Degrees: at the same Time that another, placed on the Banks of the River Tyber, one Foot above the Surface of the Water, stood at 30.0168, the attached Thermometer at 60°.6, and the Air-Thermometer at 60°.2: what, was the Height of the Building above the Level of the River? [133] See Section 375. 2dly. If the Moiety, _Half-Heat_, or mean Temperature of the Air, _is equal_ to the Standard-Temperature, to which the two Barometers are brought, by the 2d Table; the fourth Table, for _Expansion of Air_, is needless: the Height already found, in the 2d Table, being the _true_ Height of the _upper Station_. 3dly. If the Moiety, _Half-Heat_, or mean Temperature of the Air, is _less than_ the Standard-Temperature of 31°.24; subtract the mean Temperature from 31.24; and with the Remainder find the Expansion, as usual, by the 4th Table: subtract the Sum, (which is a corresponding Height in Feet and Tenths) from the Height in Feet and Tenths of the _upper_ Barometer, at the _Standard-Temperature_, in the 2d Table: and the Remainder will be the _true_ Height of the _Mountain_ or _upper Station_. Section 384, Note _a_. [134] +The question+: Near the Convent of St. Clare, in a Street called _La Strada dei Specchi_, at Rome, the _lower_ Barometer stood at 30.082, its attached Thermometer 71 Degrees, and detached ditto at 68 Degrees: on the Tarpeian Rock, or West-End of the famous Hill called The Capitol, the _upper_ Barometer was at 29.985, its attached Thermometer 70°.5, and detached ditto 76°: what was the Height of the Eminence? [135] Sadler’s _Practical Arithmetic_, Page 293. [136] The Writer has not hitherto been so fortunate as to meet with the original Memoir, containing the Particulars of this curious Experiment by Mons. Lavoisier. [137] Dr. Priestley’s Experiments and Observations relating to Air and Water. Ph. Tr. for 1785, Vol. 75, Part 1, Page 279. [138] The Diameter may be enlarged. [139] By Means of the Cradle, _both_ are more easily moved: the Muffle is prevented from adhering to the Tube; and Steam is admitted to the Borings. [140] Copper sustaining a _red_ Heat, better than Iron; the latter of which, _calcines_ with Steam, or, in cooling. Transcriber’s Notes: