Three folders of correspondence, from James Croll - the first 2 folders only have been catalogued, and which differ in detail of cataloguing, the first one being done to a high level of detail, the second only capturing the summary created by Lyell's team:
Letter to Sir Charles Lyell from James Croll regarding the velocity of light and the effects that has on the temperature of the earth during the glacial period. He mentions the theories of Foucault, Le Verrier and Legrange, 1 March 1865.
Letter enclosing an abstract of a paper containing conclusions further to a paper which was published in August 1863. This paper points out the correspondence between the character of geological climate and those which must result from a change in the earth's orbit, 6 April 1864.
Letter discussing the calculations and speculation concerning the temperature of space which ranges from -315 degrees Fahrenheit to -224 degrees Fahrenheit, 8 April 1865.
Letter referring to several works by Duperry, Nichol and A Keitz Johnston and discussing Superior and Subordinate Maxima. He asks Lyell to pass on any information he receives from the Astronomer Royal, 18 May 1865.
Letter concerning the temperature of Iceland in the glacial epoch and at the time this letter was written and how it is affected by season, position of the island and the presence of the Gulf Stream, 6 November 1865.
Letter concerning the eccentricity of the Earth's orbit which he has calculated for a million years past and to come of epochs 5000 years apart. He states that his results are favourable to the Cosmical Theory and will be published in the January edition of the Philosophical Magazine or in the December supplement, 25 December 1865.
Letter concerning the effect of the build up of ice during the glacial epoch upon the level of the ocean and his belief that the level of the ocean would not be lowered by the accumulation of ice as the level of the water would adjust itself to the altered centre of gravity of the earth, 4 January 1866.
Letter regarding modifications he has made to his Submergence Theory which held that the level of the ocean would not be lowered by the accumulation of ice due to Lyell passing on some calculations as to the amount of water needed from the oceans to form an ice-sheet of sufficient mass to alter the earth's centre of gravity. He encloses a letter to the Reader to put the matter straight and asks for Lyell's approval. 6 January 1866.
Letter regarding another alteration to his Submergence Theory which he explains in sheets which he encloses for Lyell to send to The Reader with his earlier letter (See Lyell 1/folios 593-594). His alterations concern the structure of ice caps which have a solid crust covering and a liquid nucleus, 8 January 1866.
Letter concerning the rigidity of the Earth's crust and the submergence theory. He encloses a copy of his article entitled On The Eccentricity of the Earth's Orbit, 12 January 1866.
Letter apologising to Lyell for inadvertently misrepresenting Lyell's view of the Submergence Theory causing him to write a letter of explanation to the Reader. Croll outlines how such a thing could have happened and points out why he thinks Lyell is mistaken in his objections to the theory, 16 January 1866.
Letter concerning the effect of ice-caps upon the level of the ocean and announcing the publication of an important paper by Rev. G Fisher on the subject, 8 February 1866.
Letter concerning the extent to which the centre of gravity of the earth would be displaced by ice caps 2000 feet and 3000 feet thick, 16 February 1866.
Letter concerning calculations of Charles Moore's which Lyell had sent to him and discussing his own calculations which show how much the centre of gravity of the Earth would have been displaced by the weight of ice-caps, 17 February 1866.
Letter concerning the calculations made by himself and Charles Moore as to the shift in the centre of gravity due to ice-caps and concerning Solstitial points and Perihelion in the earth's orbit, 28 February 1866.
Letter concerning the view of "the most eminent physicist that Scotland possesses", Lord Kelvin, that a paper by Mr (Douglas) Heath is full of glaring errors and that Croll expects the Philosophical Magazine for the following month to have something further on the subject, 6 March 1866.
Letter concerning the quantity of heat received from the sun between two equinoxes, the effect of Perihelion and Aphelion on the length and strength of summers and winters and the effect of the formation of ice and snow on the levels of heat given off from the earth, 17 April 1866.
Letter concerning the temperature of space in relation to the position of the earth and the sun and discussing different methods of calculating the rate at which the temperature decreases and increases depending on the amount of heat that is received from the sun, 24 April 1866.
Letter concerning the temperature of the earth in both winter and summer and how this temperature is affected by the position of the earth in relation to the sun and snow and ice throughout the world, 23 April 1866.
Letter telling Lyell that he does not have anything ready to print in the July issue of the Philosophical Magazine, 29 June 1866.
Letter concerning his calculations of the thickness of the ice sheets and the extent of the submergence which he claims are based on geological grounds. He also discusses the possible extent of the submergence, the effect on the climate of the Ice sheet and his belief that the grinding down of rock can not be attributed to floating ice but to the extent of time that the rock was covered in ice. He also states that he feels confident that the submergence and emergence both of the glacial and coal periods can be accounted for on cosmical principles, 6 July 1866.
Letter to Sir Charles Lyell from James Croll. 9 July 1866.
Second folder contains letters are summarised by Lyell as:
1) Geological grounds for submergence
2) Effects of ice and land slides
3) Paper on submergence
4) Obliquity of ecliptic
5) Meech on effects of oblquity
6) Croll on his message
7) Meech's paper
8) Abnormality presentation
9) After receiving Principles
10) Glacial drift in Norway, pavement in Glasgow drift
11) Menteath on Pyrenees miocene glacial action
12) Glacial drift near glasgow
13) Erosion of sea on rising sea bottom
14) References to arctic tree
15) Sir E. Belcher's tree
16) Interglacial
17) Croll on Drayson's theory of climate by obliquity
18) Croll on currents.