the Barometric Formuloe, ^c. 665 



the correction (+ 0-79"") is necessary, in order to bring the published barometric 

 observations to the true and real value of the observations ; but nothing of the 

 kind appears ; no, not even a slight statement in the pages of the periodical 

 containing the observations, that they require correction. Therefore, in justice 

 to myself, I am under the necessity of thus clearly stating the case, lest any 

 Member of the Academy should consider me careless or negligent in this affair. 

 Indeed, without the gift of something approaching to inspiration, it had not 

 been possible for me to have acted in this matter otherwise than I have done. 

 Having thus explained to the Academy how it has happened that I have been 

 employed (unintentionally) in misleading the Academy, — as a matter of course, 

 it is now necessary to dismiss, at once and for ever, the Table of Errors, 

 No. IV. of page 639, in order to make way for anew Table of Errors calculated 

 with correct data. 



The following Table is intended to show the Errors of Height of the Convent 

 of the Great Saint Bernard above the Geneva Observatory, calculated from cor- 

 rect data, for moments of the day, mean time, when, according to the lai-ge Table 

 of Horary Corrections {vide Table III,, page 634, Table X., page 650 ; also 

 Table XL, page 656), the horary correction vanishes. This new Table con- 

 tains also the moments, mean time, of sunrise and sunset, for the middle day of 

 each month of the year, for the mean latitude of the Convent and Observatory 

 (viz., 46° 2' North). The correct data for the year 1855, by means of which 

 the contents of this Table have been calculated, may be found in the " Archives 

 des Sciences Physiques et Naturelles, Bibliotheque Universelle de Geneve," 

 Juillet, 1856, tome 32, de la 4"' serie, No. 127, under the Article "Eesume 

 Meteorologique de I'annee 1855, pour Geneve et le Grand Saint Bernard," par 

 M. le Professeur Plantamour, commencing at page 177 of the "Archives des 

 Sciences Physiques et Naturelles," and terminating at page 203 of the same 

 Archives, &c. The Archives here alluded to are to be found in the Library of 

 the Royal Irish Academy. The true height of the Convent above the Obser- 

 vatory, by extremely accurate spirit-levelling = 2070'34 metres ; the mean lati- 

 tude of the Convent and Observatory = 46° 2' North ; horary correction = 0, 

 according to Tables X. and XI.; vide pages 650 and 656; also Table III., 

 page 634. 



4 s 2 



