532 
THE  ADMIEALTT  ASTEONOMICAL  EXPEEIMENT 
The  case  is  therefore  altogether  most  deserving  of  further  inquiry,  which,  to  be  suc- 
cessful, must  be  prefaced  by  more  observations,  not  only  at  many  different  points  in  the 
Canarian  Archipelago,  but  at  several  levels  in  the  atmosphere ; for  on  the  different 
superimposed  currents  of  air,  and  their  respective  strata  of  cloud,  it  is  very  evident  that 
a large  part  of  the  anomalies  of  terrestrial-surface  climate  most  intimately  depend. 
(11.)  Tidal  Observations. 
The  exposed  condition  of  the  Santa  Cruz  beach  offered  more  difficulties  to  carrying 
on  tide  observations  than  had  been  expected,  or  than  I should  have  been  able  to  over- 
come, but  for  the  warm  cooperation  of  Mr.  Levtis  Hamilton,  and  more  particularly  of 
Don  Feancisco  Aguilae,  the  Engineer  of  the  Mole,  who  beiug  engaged  on  some  repairs 
of  that  structure,  kindly  undertook  the  building  of  such  a vertical  trough  as  should  be 
secure  from  the  severe  swell  usually  prevailing.  This  tide-gauge  was  only  completed  on 
the  day  of  my  leaving  Santa  Cruz : and  I could  do  Kttle  more  than  admire  the  regularity' 
of  the  rise  of  the  rod,  though  the  tide  came  in  with  great  rollers;  test  the  divisions 
engraved  on  it,  which  proved  to  be  English  feet  and  inches ; and  arrange  for  the  making 
of  some  observations,  which  the  Don  most  obligingly  offered  to  superintend. 
The  first  point  to  be  inquired  into  was  the  probable  existence  of  any  liitherto  un- 
recognized anomaly  in  the  tide-wave.  To  detect  any  such  featui’e,  Don  Feaacisco 
Aguilae  kept  up  observations  at  five-minute  intervals,  from  5 o’clock  in  the  morning  of 
the  13th  to  9 o’clock  in  the  evening  of  the  16th  of  October,  1856. 
On  projecting  these  numerous  and,  I believe,  most  carefully  registered  measures, 
the  tide-wave  appeared  most  satisfactorily  single ; and  on  communicating  them  to 
Dr.  Whewell,  he  expressed  himself  perfectly  content  Avith  their  freedom  from  any 
feature  requiring  observations  at  other  instants  than  about  the  times  of  high  and  low 
water  in  the  ordinary  manner. 
Matters  were  thus  far  cleared  and  made  ready  for  the  next  investigation ; but  before 
the  requisite  instructions  could  reach  Santa  Cruz,  the  alterations  of  the  Mole  had  reached 
the  part  where  the  tide-gauge  stood,  and  compelled  its  removal.  The  authorities  were 
again  very  obliging  in  giving  their  permission  to  the  machine’s  re-erection  at  a different 
spot ; but  this  I was  not  able  to  undertake. 
The  Don’s  observations,  already  alluded  to,  are  contained  in  full  in  volume  1,  and  give 
the  following  times  and  heights  of  low  and  high  water : — 
