James Croll: Timing is Everything

It’s easy to  tell middle and high school students that “scientists say ‘seeing is believing'” while “non-scientists say ‘believing is seeing.'”

That’s not incorrect.

Still, a belief in some general principles is helpful to geologists, because things get complicated in the field.

However tough we’ve got it, the Victorians had a worse time as they established the new science of geology in Britain.  Still, one of them, James Croll got it right about climate change and proved to be way ahead of his time.

Age of Controversy

Interwoven strands of religion and natural philosophy were unraveling in the 1800s as new discoveries changed everyone’s preconceptions.

How old was the Earth really, and how could you reconcile its great age with the Bible?  How did God manage great extinctions in the past, apparently associated with that Frenchman’s newfangled  idea of an “ice age”?

Factions existed.  Great debates were held.  A few correlations of style, if not content, could be drawn between the arguments of those days and today’s furor over climate change.

Scotsman James Croll was in the thick of it.

A Self-Educated Fellow

Born on a small farm in Perthshire, Croll was prone to headaches.  This, along with “family exigencies,” limited his formal schooling.

He made little progress in home schooling until the first issue of Penny Magazine caught his attention.  After that he read more and more, later saying :

At first I became bewildered, but soon the beauty and simplicity of the conceptions filled me with delight and astonishment, and I began then in earnest to study the matter. . . . Even at the very commencement of my studies it was not the facts and details of the physical sciences which riveted my attention, but the laws and principles which they were intended to illustrate. This necessarily determined me to study the sciences in something like systematic form; for, in order to understand a given law, I was generally obliged to make myself acquainted with the preceding law or conditions on which it depended. I remember well that, before I could make headway in physical astronomy . . . I had to go back and study the laws of motion and the fundamental principles of mechanics. In like manner I studied pneumatics, hydrostatics, light, heat, electricity, and magnetism. I obtained assistance from no one. In fact, there were none of my acquaintances who knew anything whatever about these subjects.

Ill health, injuries and a “strong and almost irresistible propensity toward study which prevented me devoting my whole energy to business” put an end to his first attempts for a career.

In 1859, he became a janitor in the Andersonian College and Museum in Glasgow, where he had full access to the library, which opened up the world of physical science for him.

Starting  in 1864, he wrote a series of papers for the Philosophical Magazine and the Reader over ten years that became the basis for his most famous work, Climate and Time in Their Geological Relations (1885).

The frontispiece of Croll's "Climate and Time."

The frontispiece of Croll’s “Climate and Time.” (Click to enlarge image.)

Croll’s papers impressed the scientific establishment. He began correspondence with some noted scientists of the day, and the Geological Society of Glasgow made him an honorary associate.

When he was offered a job in the Scottish branch of the Geological Survey as resident surveyor and clerk in Edinburgh, he failed the required civil service exam.  They made an exception for him, allowing his papers as proof of his writing ability and his calculations of Earth’s orbital variations as evidence of his mastery of mathematics.

Eventually Croll was elected as a Fellow to the Royal Society and also was awarded an honorary degree by the University of St. Andrews.  He continued to work on natural science and metaphysics until ill health forced him to retire in 1880.

Croll-Milankovitch Cycles

Many listened to what Croll had to say (PDF) about slight variations in Earth’s orbit as the cause of ice age and climate change.  Great men, like Charles Lyell (PDF), even applied his ideas to their own works.

Few took him literally, though, because he argued from principles (believing) and not evidence (seeing), according to Diarmid Finnegan.

Lord Kelvin himself read Croll’s obituary to the Royal Society after his death in 1890, saying that Croll’s astronomical theory “presented a vera causa for some of the changes of climate which have occurred in geological history, although we can scarcely consider it adequate to be so powerful and exclusive a factor as Croll endeavoured to make it.”

Croll’s theory faded from prominence after his death, as there was no evidence yet for multiple ice ages.  The early 20th century astrophysicist Milutin Milankovitch did praise Croll as he developed a mathematical model for a similar theory, but Milankovitch’s own work was also overlooked.

It wasn’t until the 1970s that evidence of multiple and cyclical ice ages was finally found on the sea floor, showing that Croll and Milankovitch had been right.

Timing is everything

In calling Croll a “metaphysical geologist,” Diarmid Finnegan points out that the Scot’s Calvinism was based on the American Jonathan Edwards‘ “theological determinism,” tempered by Scottish “common sense realism.”

Croll believed “that human perception of the external world is reliable, that nature is intelligible, and that whatever begins to exist has a cause.”  However, according to Finnegan, he also felt that there is no such thing as a self-determining cause – God alone is the cause of everything.

When it came to science, Croll’s belief system wasn’t limited by the theological considerations that gave some of his contemporaries difficulties over evidence that the Earth was older than the Bible suggested.  Croll could thus envision events over a long enough time span to imagine cyclical ice ages happening on Earth.

There was a down side to this.  Both his “metaphysical investigations and his scientific ones . . . began with fixed ‘principles’ rather than observed facts.” Since scientists wanted facts rather than unsupported hypotheses,  Croll’s ideas never were fully accepted during his life or long afterwards.

Had he lived later, or had the technology existed back then to dredge up sea bed cores, James Croll would probably be one of history’s most famous figures.

Timing is indeed everything.


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