﻿1874.] 
  

  

  President's 
  Address. 
  

  

  71 
  

  

  A 
  discovery 
  like 
  this 
  opened 
  up 
  a 
  new 
  field 
  of 
  research, 
  which 
  Mr. 
  

   Lockyer 
  was 
  not 
  backward 
  in 
  exploring. 
  One 
  of 
  the 
  firstfruits 
  of 
  the 
  

   application 
  of 
  the 
  method 
  was 
  the 
  discovery 
  of 
  a 
  continuous 
  luminous 
  

   gaseous 
  envelope 
  to 
  the 
  sun, 
  which 
  he 
  calls 
  the 
  chromosphere, 
  of 
  

   which 
  the 
  prominences 
  are 
  merely 
  local 
  aggregations. 
  Evidence 
  was 
  

   further 
  obtained 
  of 
  gigantic 
  convulsions 
  at 
  the 
  surface 
  of 
  the 
  sun, 
  which 
  

   were 
  revealed 
  by 
  slight 
  alterations 
  of 
  refrangibility 
  in 
  the 
  lines, 
  observed 
  

   in 
  a 
  manner 
  similar 
  to 
  that 
  in 
  which 
  Mr. 
  Huggins 
  had 
  determined 
  the 
  

   relative 
  velocity 
  of 
  approach 
  or 
  recess 
  of 
  the 
  Earth 
  and 
  Sirius. 
  

  

  The 
  interpretation 
  of 
  spectroscopic 
  solar 
  phenomena 
  required 
  a 
  reexami- 
  

   nation 
  in 
  several 
  respects 
  of 
  the 
  spectroscopic 
  features 
  of 
  artificial 
  sources 
  

   of 
  light. 
  Among 
  these 
  researches 
  special 
  mention 
  must 
  be 
  made 
  of 
  Mr. 
  

   Lockyer's 
  classification 
  of 
  the 
  lines 
  due 
  to 
  the 
  metals 
  of 
  the 
  electrodes 
  be- 
  

   tween 
  which 
  an 
  induction 
  discharge 
  was 
  passed, 
  according 
  to 
  their 
  "length,'' 
  

   i. 
  e. 
  the 
  distance 
  from 
  the 
  electrodes 
  to 
  which 
  they 
  could 
  respectively 
  be 
  

   traced. 
  This 
  led 
  to 
  the 
  explanation 
  of 
  various 
  apparent 
  anomalies 
  as 
  to 
  

   the 
  presence 
  or 
  absence 
  of 
  certain 
  dark 
  lines 
  in 
  the 
  solar 
  spectrum, 
  and 
  to 
  

   the 
  detection 
  of 
  additional 
  elements 
  in 
  the 
  sun, 
  especially 
  potassium, 
  an 
  

   element 
  which, 
  though 
  so 
  common 
  on 
  the 
  earth 
  and 
  so 
  easily 
  detected 
  by 
  

   spectral 
  analysis, 
  had 
  not 
  previously 
  been 
  proved 
  to 
  exist 
  in 
  the 
  sun, 
  be- 
  

   cause 
  the 
  attention 
  of 
  observers 
  had 
  been 
  turned 
  in 
  a 
  wrong 
  direction, 
  as 
  

   was 
  shown 
  by 
  these 
  researches. 
  

  

  Nor 
  was 
  it 
  only 
  in 
  relation 
  to 
  solar 
  physics 
  that 
  these 
  researches 
  bore 
  

   fruit. 
  They 
  led 
  to 
  a 
  quantitative 
  determination 
  in 
  many 
  cases, 
  by 
  means 
  

   of 
  the 
  spectroscope, 
  of 
  the 
  proportion 
  of 
  the 
  constituents 
  in 
  an 
  alloy, 
  and 
  

   afforded 
  new 
  evidence 
  of 
  the 
  extent 
  to 
  which 
  impurities 
  are 
  present 
  even 
  

   in 
  substances 
  deemed 
  chemically 
  pure. 
  

  

  The 
  Medal 
  was 
  received 
  by 
  Mr. 
  Lockyer. 
  

  

  A 
  Eoyal 
  Medal 
  has 
  been 
  awarded 
  to 
  Mr. 
  Henry 
  Clifton 
  Sorby, 
  F.R.S., 
  

   " 
  for 
  his 
  Researches 
  on 
  Slaty 
  Cleavage 
  and 
  on 
  the 
  minute 
  Structure 
  of 
  

   Minerals 
  and 
  Rocks 
  ; 
  for 
  the 
  construction 
  of 
  the 
  Micro-Spectroscope, 
  

   and 
  for 
  his 
  Researches 
  on 
  Colouring-matters." 
  

  

  The 
  principal 
  grounds 
  on 
  which 
  Mr. 
  Sorby's 
  claims 
  to 
  a 
  Royal 
  Medal 
  

   rest 
  are 
  the 
  following 
  : 
  — 
  

  

  1. 
  His 
  long-continued 
  study, 
  and 
  his 
  successful 
  application 
  of 
  the 
  

   microscope 
  to 
  the 
  solution, 
  of 
  problems 
  in 
  petrology. 
  

  

  2. 
  His 
  employment 
  of 
  .the 
  prism 
  in 
  conjunction 
  with 
  the 
  microscope 
  

   for 
  the 
  analysis 
  of 
  the 
  colours 
  transmitted 
  by 
  substances, 
  as 
  well 
  organic 
  

   as 
  inorganic. 
  

  

  Though 
  Mr. 
  Sorby's 
  labours 
  during 
  the 
  last 
  ten 
  years 
  have 
  been 
  more 
  

   particularly 
  devoted 
  to 
  observations 
  of 
  the 
  latter 
  class, 
  his 
  work, 
  extend- 
  

   ing 
  over 
  a 
  period 
  that 
  commenced 
  in 
  1849, 
  is 
  represented 
  in 
  the 
  Catalogue 
  

   of 
  Scientific 
  Papers 
  (limited 
  by 
  the 
  year 
  1863) 
  by 
  no 
  less 
  than 
  47 
  

   memoirs. 
  Among 
  the 
  more 
  remarkable 
  of 
  these 
  must 
  be 
  mentioned 
  the 
  

  

  