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CONTENTS.
PREFATORY NOTE ON THE RECENT PROGRESS AND PRESENT
ASPECT OF THE THEORY OF GLACIERS
I. ON A REMARKABLE STRUCTURE OBSERVED BY THE AUTHOR
IN THE ICE OF GLACIERS [1841]
Obscurity of the Theory of Glacier Formation...Ribboned Struc-
ture described...Its Course traced on the Glaciers of the
Aar and Rhone ... Probably perpendicular to Lines of
greatest Pressure... Also perpendicular to Fissures or Cre-
Analogy to Slaty Cleavage in Rocks... Physical
Cause of both perhaps similar.
vasses...
II. FIRST LETTER ON GLACIERS. Addressed to PROFESSOR
JAMESON [1842]
Account of the First Experiments, undertaken in June 1842,
to determine the Laws of Motion of the Mer de Glace of
Chamouni.
III. SECOND LETTER ON GLACIERS. Addressed to PROFESSOR
The Laws of Motion of the Mer de Glace farther stated.
IV. THIRD LETTER ON GLACIERS, Addressed to PROFESSOR
The Laws of Structure of Glaciers generally detailed...The
"Dirt-Bands" described...Mechanical Theory of the Struc-
ture... Dirt-Bands correspond to Annual Intervals... Glaciers
probably move in Winter.
Page
xiii
1
9
13
17
Change of Level and General Appearance of the Glacier in the
month of September...Collapse of the Walls of the Cre-
vasses....Moulins.... Veined Structure....Direction of the
Crevasses...Both Veined Structure and Crevasses renewed
from time to time... The Motion of a Glacier resembles that
of a Viscid Fluid-Objections to the Dilatation Theory...
What the Cold of Winter may be supposed to accomplish.
VI. FIFTH LETTER ON GLACIERS.
Addressed to the Right
Honourable EARL CATHCART [1844]
Motion of the Mer de Glace in the year 1842-3... Winter Move-
ment... The Veined Structure reproduced at the foot of an
Ice Cascade...Cuts the Medial Moraines... Wrinkles in the
Ice of the Glacier du Géant and that of Grindelwald,
probably corresponding to the position of the Dirt-Bands...
An Ancient Moraine at Chamouni.
VII. SIXTH LETTER ON GLACIERS. Addressed to the Right
Analogies of Glaciers to Lava Streams....Observations on
Mount Vesuvius...Moraines of Lava Streams. Some Objec-
tions to the Plastic or Viscous Theory of Glaciers considered
...Verticality of Crevasses accounted for.
VIII. SEVENTH LETTER ON GLACIERS.-ON THE VEINED STRUC-
ture of the ICE, Addressed to the Rev. Dr. WHEWELL,
Master of Trinity College, Cambridge [1844]
Mechanical Considerations tending to explain the Forms of the
Veined Structure under different Conditions.
IX. Eighth LETTER ON GLACIERS. Addressed to PROFESSOR
JAMESON [1844]
Observations on the Motion of the Glacier of Aletsch... Experi-
ments on the Plasticity of the Ice of the Mer de Glace, by
Observing the Distortion of a Limited Space of Ice devoid
of Crevasses...Movement of a Glacier of the Second Order
8000 feet above the Sea.
35
43
56
61
ix
X. NINTH Letter on GLACIERS. Addressed to PROFESSOR
JAMESON [1845] .
Remarks on the Recent Observations made on the Glacier
of the Aar (in 1844) by direction of M. Agassiz...New Con-
firmation of the Plastic Theory....Condensation of the
Glacier in its downward course in consequence of Frontal
Resistance...Continuity of Motion...Motion accelerated in
Fine Weather-Excess of Central Velocity of the Glacier
...Motion of Glaciers of Second Order, and of Snow Beds.
XI. ILLUSTRATIONS OF THE VISCOUS THEORY OF GLACIER
MOTION.*-PART I. CONTAINING EXPERIMENTS ON THE
FLOW OF PLASTIC BODIES, AND OBSERVATIONS ON THE
PHENOMENA OF LAVA STREAMS [1845]
21. Plastic Models. 2. Analogy of Glaciers to Lava
Streams...Note on the Velocity of Lava.
XII. ILLUSTRATIONS OF THE VISCOUS THEORY OF GLACIER
MOTION.*-PART II. AN ATTEMPT TO ESTABLISH BY
OBSERVATION THE PLASTICITY OF GLACIER ICE [1845]
? 3. De Saussure's Theory. 24. Modifications of De Saus-
sure's Theory. 25. Experiments at Chamouni on the
Plasticity of Ice.
XIII. ILLUSTRATIONS OF THE VISCOUS THEORY OF GLACIER
MOTION.*-PART III. [1846]
7. On
? 6. On the Motion of Glaciers of the Second Order.
the Annual Motion of Glaciers, and on the Influence of
Seasons. 28. Summary of the Evidence adduced in favour
of the Theory...Glacier not a Mass of Fragments...
Argument from the Equable Progression of Glaciers...
Formation of Crevasses... Law of Velocities...Ablation of the Surface... Plasticity; Veined Structure.
Addition on the Plasticity of Ice on the Small Scale
* From the Philosophical Transactions.
68
77
95
119
167
XIV. ELEVENTH LETTER ON GLACIERS.
Addressed to PRO-
FESSOR JAMESON [1846]
169
Observations on the Depression of the Glacier Surface...
Ablation and Subsidence distinguished and ascertained...
On the Relative Velocity of the Surface and Bottom of a
Glacier.
XV. TWELFTH LETTER ON GLACIERS. Addressed to PRO-
On the Extraordinary Increase of the Glacier of La Brenva
from 1842 to 1846...Its Motion in Winter, as observed
by M. Guicharda...Observations on the Veined Structure
in 1846, and Experimentum Crucis respecting its Origin,
with measurements of the motion of the Ice...Analogy
from the motion of the Rhone.
XVI. THIRTEENTH LETTER ON GLACIERS.
176
Acceleration of the Surface Motion of Glaciers confirmed...
Velocity of the Mer de Glace in the Summer of 1846 at
Stations C, D, P, and R...Velocity of the Glacier of
Talèfre, near its point of Discharge...Discovery of a Knap-
sack ten years buried in the Ice, and deduction of the
motion...The Glacier of Nant Blanc visited, and its Motion
determined... The Glacier of Miage revisited, and motion
measured...On the Conversion of the Névé into Ice...
Congelation of Infiltrated Water not necessary to produce
the Veined Structure... An attempt to explain the appa-
rent rejection of Stones from the Glacier... Ridges of Ice
in certain parts of Glaciers due to the bruising effect of
intense Pressure... Three Orders of discontinuity, Ridges,
Crevasses, Veined Structure.
XVII. FOURTEENTH LETTER ON GLACIERS. Addressed to PRO-
FESSOR JAMESON [1847]
On the Variation of the Motion at different Seasons...Obser-
vations on the Glacier of the Aar, considered and com-
pared with the Author's results.
187
205
XVIII. FIFTEENTH LETTER ON GLACIERS. Addressed to the
Rev. Dr. WHEWELL [1848].
Observations on the Analogies derived from Mud-Slides
on a Large Scale, and from some Processes in the Arts
in favour of the Viscous Theory of Glaciers.
Land-slips as observed by M. Collin... Mr. Milward on the
Phenomena of a large Mud-slide at Malta, and on the
Cause of the Dirt-Bands and Wrinkles of Glaciers...Con-
nection with Frontal Dip...Surfaces of Detrusion in Iron
Turnings, attended with Vertical Accumulation of
Material.
XIX. SIXTEENTH LETTER ON GLACIERS. Addressed to PRO-
FESSOR JAMESON [1850]
Observations on the Movement of the Mer de Glace down to
1850...Observations by Balmat, at different seasons, in
continuation of those formerly detailed...On the gradual
passage of Ice into the Fluid State; observations of M.
Person...Notice of an undescribed Pass of the Alps, from
Chamouni to Orsières by the Glaciers of Tour and Salena.
XX. ON SOME PROPERTIES OF ICE NEAR ITS MELTING POINT
210
220
[1858]
XXI. ON GLACIERS IN GENERAL*
APPENDIX.
No. I. AN ATTEMPT TO ILLUSTRATE THE ORIGIN OF
BANDS" IN GLACIERS. By A. MILWARD, Esq.
No. II. MR. FARADAY ON THE PROPERTIES OF ICE
"DIRT-
* From the Encyclopædia Britannica, eighth edition.
228
233
261
265