50 Lord Rayleigh, On the measurement [Nov. 26, 



Fig. II. Longitudinal section of the apex of the leaf of Sagittaria 

 Monte Vidiensis. 



v = vascular bundle. 

 t = tracheide tissue. 

 e = cells corresponding to the epithem tissue of Dicotyledons. 



Fig. III. Longitudinal section of a gland of Polypodium aureum. 

 v = vascular bundle. 

 t = tracheide tissue. 

 e = excreting epidermis. 



Fig. IY. Longitudinal section of the nectary of the cotyledon of 

 Bicinus communis (after Bonnier). 

 v = vascular bundle. 

 s = surface of nectary. 



Fig. V. Longitudinal section through the spur at the base of the 

 petal of Nigella arvensis (after Behrens). 

 v = vascular bundle. 

 n = nectary surface. 



November 26, 1883. 



Mr Glaisher, Peesident, in the Chair. 



The following were duly balloted for and elected Fellows of 

 the Society : — 



Prof. Macalister, M.A., F.R.S., St John's College. 

 Mr J. C. McConnel, B.A., Clare College. 

 Mr E. J. C. Love, B.A., St John's College. 



The following communications were made to the Society : 



(1) On the measurement of electric currents. By Lord Ray- 

 leigh, M.A., F.R.S. ► . ■ 



Perhaps the simplest way of measuring a current of moderate 

 intensity when once the electro-chemical equivalent of silver is 

 known, is to determine the quantity of metal thrown down by the 

 current in a given time in a silver voltameter. According to 

 Kohlrausch the electro-chemical equivalent of silver is in c. G. S. 

 measure L136 x 10~ 2 , and according to Mascart 1124 x 10~ 2 . Ex- 

 periments conducted in the Cavendish Laboratory during the past 

 year by a method of current weighing described in the British 

 Association Report for 1882 have led to a lower number, viz. 

 1*119 x lO - ' 2 . At this rate the silver deposited per ampere per 

 hour is 4 - 028 grams, and the method of measurement founded 



