Mr.  E.  V.  Neale  on  Glacier-motion.  105 
accumulate  till  the  resistance  was  overcome.  Hence  the  particles 
of  glacier-ice,  though  to  our  senses  they  seem  stationary,  are 
always  slowly  moving,  under  the  influence  of  the  thrust  behind 
them,  gliding  past  the  sides  of  their  mountain-bed  and  past  each 
other  with  velocities  varying  according  to  the  direction  and  in- 
tensity of  the  lines  of  pressure  acting  upon  them. 
In  regard  to  this  motion,  we  must  also  bear  in  mind  that  the 
accelerative  action  of  the  particles  moving  in  front  of  any  given 
particle  must  always  in  great  part  counterbalance  any  retarding 
action  of  those  moving  at  its  sides;  so  that  the  accumulated 
pressure  exerted  by  those  behind  it  in  order  to  keep  up  its 
movement  would  be  limited  to  the  difference  between  these 
two  actions,  which  is  probably  small. 
It  appears,  then,  not  difficult  to  account  for  the  motions  ob- 
served iu  glaciers  by  the  accumulated  effect  of  gravitation.  But 
if  the  explanation  here  given  is  the  true  one,  there  ought  to  be 
other  motions  observable  among  the  particles  of  a  glacier,  due 
to  the  impact  of  the  bottom  of  the  glacier  on  the  irregularities 
of  the  surfaces  over  which  it  slides,  which  must,  I  conceive,  pro- 
duce lines  of  pressure  reflected  upwards  obliquely  from  the  bottom 
through  the  advancing  mass.  Accordingly  we  do  find  the  evi- 
dence of  such  pressures  in  the  direction  of  the  ribboned  struc- 
ture often  noticed  in  glacier-ice,  the  thickness  of  the  bands  being 
probably  determined  by  the  mass  of  neve  consolidated  into  ice 
from  year  to  year. 
2nd.  The  force  adduced  in  the  preceding  explanation  ap- 
pears sufficient  to  account  for  the  movements  of  the  particles  of 
a  glacier,  even  though  their  adhesion  to  each  other  should  be  as 
great  as  Canon  Moseley's  experiments  indicate.  But  I  cannot 
feel  quite  satisfied  with  the  results  obtained  by  him.  We  know 
that  ice  forms  in  thin  layers,  which  lie  one  on  the  top  of  another. 
Canon  Moseley's  experiments  on  the  shearing-foYce  required  to 
separate  the  particles  of  ice  were  made,  I  believe,  by  placing 
weights  on  the  surface  of  a  block  of  ice  resting  on  a  solid  sup- 
port, so  that  the  weight  would  tend  to  compress  the  layers  of  ice 
and  bring  their  particles  into  closer  contact.  Now  the  increase 
of  molecular  action  appears  to  follow  a  ratio  much  above  that  of 
the  inverse  square.  May  not,  therefore,  the  adhesive  force  of 
the  particles  of  ice  have  been  materially  increased  by  the  method 
used  to  ascertain  it  ?  If  the  motion  of  glaciers  is  to  be  subjected 
to  strict  mathematical  reasoning,  as  is  much  to  be  desired,  it 
seems  to  me  that  experiments  are  needed  by  which  the  adhesive 
force  of  ice  shall  be  tested  in  a  manner  more  nearly  approaching 
the  action  of  the  pressure  in  a  glacier  upon  it,  i.  e.  by  means  of 
a  force  applied  at  one  end  of  a  block  of  ice  held  fast  by  lateral 
compression  and  its  own  weight ;  and  until  this  has  been  done,, 
