458 Royal Society : — 



The paper concludes with a statement of the mode of procedure 

 which the author has found most suitable for examining the tissue 

 which forms the subject of his inquiry. 



" Account of the Construction of a Standard Barometer, and of 

 the Apparatus and Processes employed in the Verification of Baro- 

 meters at the Kew Observatory." By John Welsh. 



After stating the results of experiments, made under the superin- 

 tendence of the Kew Committee, for the construction of a barometer 

 tube of large diameter by the usual method of boiling the mercury 

 in the tube, the author proceeds to describe a method of filling a 

 tube with the aid of an air-pump. In this process, which is fully 

 detailed in the paper, the tube is so constructed, that when the air 

 has been extracted from it, the mercury enters by atmospheric 

 pressure, provision being made for entirely removing the air which 

 the air-pump has failed to extract. By this method a barometer 

 tube of 1-1 inch internal diameter has been satisfactorily prepared at 

 the Kew Observatory. The author then describes the mounting and 

 mode of observing the standard barometer, proceeds to explain the 

 processes adopted in the verification of barometers, and gives a 

 detailed description of the apparatus for determining the errors of 

 barometers at different atmospheric pressures. 



" On the Lunar-diurnal MagneticVariation at Toronto." By Major- 

 General Edward Sabine, R.A., D.C.L., Treas. and V.P.R.S. 



This paper contains the results of an investigation into the moon's 

 diurnal influence on the horizontal and vertical components of the 

 magnetic force at Toronto, and the consequent deduction of the lunar- 

 diurnal variations of the inclination and of the total force at that 

 station. The observations from which the results were obtained 

 consisted of five years of hourly observation of the bifilar and ver- 

 tical force magnetometer, ending June 30, 1848, from which the 

 disturbances of largest amount had been separated as described in a 

 paper previously communicated (Phil. Trans. 1856, Art. XV.). The 

 results derived from the mean of the five years are confirmed by 

 the accord which is shown of the means of each of the half-periods 

 into which the observations of the five years are divided for that 

 purpose. 



To complete the view of the moon's diurnal influence on the mag- 

 netic elements at Toronto, a recalculation has been made of the 

 lunar-diurnal variation of the declination from the mean of six years 

 of hourly observation, ending June 30, 1848, employing the more 

 perfect normals derived from the exclusion of the larger disturbances, 

 as described in the paper above referred to (Phil. Trans. Art. XV. 

 1856) ; and the confirmation is shown of the mean result of the six 

 years by the accordance of three separate portions of two years each, 

 into which the whole period of six years has been divided for that 

 purpose. 



From these premises the author draws the following conclusions : 



1 . The three magnetic elements concur in showing that the moon 

 exercises a sensible magnetic influence at the surface of the earth, 



