﻿Geology. 
  249 
  

  

  tint 
  of 
  mauve. 
  The 
  explosions 
  sounded 
  like 
  the 
  sharp 
  crack 
  of 
  a 
  

   whip 
  and 
  the 
  associated 
  luminosity 
  was 
  sufficiently 
  intense 
  and 
  

   extended 
  to 
  light 
  up 
  the 
  interior 
  of 
  the 
  observatory. 
  The 
  appar- 
  

   ent 
  diameter 
  was 
  a 
  little 
  less 
  than 
  that 
  of 
  the 
  moon. 
  No 
  other 
  

   strokes 
  of 
  lightning 
  occurred 
  during 
  the 
  entire 
  day. 
  — 
  Annates 
  de 
  

   Phys. 
  y 
  vol. 
  v, 
  pp. 
  365, 
  366 
  ; 
  May-June, 
  1916. 
  h. 
  s. 
  u. 
  

  

  7. 
  A 
  Laboratory 
  Course 
  of 
  Practical 
  Electricity 
  ; 
  by 
  Mau- 
  

   rice 
  J. 
  Archbold. 
  Pp. 
  ix, 
  222. 
  New 
  York, 
  1916 
  (The 
  Mac- 
  

   millan 
  Co.). 
  — 
  This 
  manual 
  may 
  be 
  used 
  in 
  connection 
  with 
  any 
  

   text-book 
  and 
  the 
  experimental 
  work 
  suggested 
  is 
  supposed 
  to 
  

   be 
  supplemented 
  by 
  lectures 
  and 
  demonstrations. 
  Each 
  page 
  is 
  

   essentially 
  a 
  skeleton 
  of 
  a 
  laboratory 
  report 
  so 
  arranged 
  that 
  the 
  

   student 
  has 
  to 
  supply 
  the 
  missing 
  words 
  in 
  sentences, 
  enter 
  

   numerical 
  data 
  in 
  ruled 
  blank 
  tables, 
  and 
  draw 
  graphs 
  on 
  cross- 
  

   ruled 
  areas. 
  Wiring 
  diagrams 
  for 
  all 
  of 
  the 
  experiments 
  are 
  

   given 
  in 
  the 
  appendix. 
  The 
  number 
  of 
  exercises 
  for 
  each 
  of 
  the 
  

   first, 
  second, 
  third, 
  and 
  fourth 
  semesters 
  is 
  27, 
  25, 
  24 
  and 
  22, 
  respec- 
  

   tively. 
  To 
  make 
  the 
  work 
  practical, 
  as 
  many 
  of 
  the 
  tests 
  as 
  

   possible 
  are 
  given 
  with 
  commercial 
  apparatus. 
  The 
  experiments 
  

   are 
  carefully 
  graded 
  from 
  very 
  elementary 
  qualitative 
  manipula- 
  

   tion 
  of 
  magnets 
  to 
  more 
  advanced 
  work, 
  such 
  as 
  : 
  " 
  Methods 
  of 
  

   Connecting 
  Polyphase 
  Transformers," 
  etc. 
  The 
  book 
  is 
  bound 
  

   in 
  the 
  loose-leaf 
  manner 
  so 
  that 
  the 
  instructor 
  may 
  change 
  the 
  

   order 
  of 
  the 
  experiments. 
  h. 
  s. 
  it. 
  

  

  8. 
  The 
  National 
  Physical 
  Laboratory. 
  Report 
  for 
  the 
  Year 
  

   1915-16. 
  Pp. 
  80. 
  Teddington, 
  1916 
  (W. 
  F. 
  Parrott).— 
  "The 
  

   work 
  of 
  the 
  Laboratory 
  during 
  the 
  past 
  year 
  has 
  been 
  greatly 
  

   affected 
  by 
  circumstances 
  arising 
  out 
  of 
  the 
  war. 
  A 
  considerable 
  

   part 
  of 
  the 
  ordinary 
  research 
  work 
  has 
  been 
  in 
  abeyance 
  ; 
  in 
  its 
  

   place 
  a 
  large 
  number 
  of 
  special 
  investigations 
  have 
  been 
  under- 
  

   taken 
  for 
  Government 
  Departments, 
  and 
  the 
  testing 
  work 
  for 
  Gov- 
  

   ernment 
  Departments 
  has 
  also 
  very 
  greatly 
  increased. 
  There 
  has 
  

   been 
  a 
  reduction 
  in 
  other 
  test 
  work, 
  and 
  the 
  Laboratory 
  has 
  thus 
  

   been 
  almost 
  entirely 
  employed 
  with 
  Government 
  work." 
  For 
  

   these 
  reasons 
  the 
  report 
  is 
  of 
  much 
  less 
  general 
  scientific 
  interest 
  

   than 
  usual. 
  In 
  the 
  appendix 
  is 
  given 
  a 
  description 
  of 
  the 
  new 
  

   aeronautics 
  buildings 
  which 
  were 
  constructed 
  in 
  a 
  very 
  short 
  

   time. 
  The 
  text 
  is 
  followed 
  by 
  large 
  diagrams 
  of 
  the 
  new 
  struc- 
  

   tures 
  in 
  plan 
  and 
  elevation, 
  together 
  with 
  photographs 
  of 
  the 
  ex- 
  

   teriors 
  both 
  of 
  the 
  buildings 
  and 
  of 
  the 
  wind-channels. 
  

  

  h. 
  s. 
  u. 
  

  

  II. 
  Geology. 
  

  

  1. 
  Lnvestigations 
  of 
  Gravity 
  and 
  Lsostasy 
  ; 
  by 
  William 
  

   Bowie, 
  Chief 
  of 
  Division 
  of 
  Geodesy, 
  U. 
  S. 
  Coast 
  and 
  Geodetic 
  

   Survey. 
  Special 
  Publication 
  No. 
  40, 
  TJ. 
  S. 
  Coast 
  and 
  Geod. 
  Surv. 
  

   Pp. 
  196, 
  page 
  figs. 
  1-9, 
  in 
  pocket 
  10-18. 
  Washington, 
  1917. 
  — 
  

   This 
  publication 
  extends 
  and 
  elaborates 
  the 
  lines 
  of 
  investigation 
  

   begun 
  in 
  previous 
  publications. 
  In 
  1912 
  Bowie 
  published 
  the 
  

   results 
  of 
  observations 
  at 
  124 
  gravity 
  stations 
  in 
  the 
  United 
  

  

  