H H Thomas, the Geological Survey and the First World War

H H Thomas (P585032)

In September 1916 the Geological Survey was contacted by the Admiralty Compass Department asking for assistance with the design of aircraft compasses. The problem was with the compass point and cup which were part of the bearing that allowed the compass needle to move. Herbert H Thomas, a petrographer at the Survey, was given the task of finding a solution. The point and cup were both made out of sapphire, which caused the point to develop flaws and cracks. In a report Thomas and Survey chemist E G Radley wrote:

Page of report by Thomas and Radley (GSM/DR/St/A/20)

“It appeared desirable that sapphire should be retained as the material for the cup, and therefore we sought some slightly less hard substance suitable for the points.

   Agate, from its closely felted microscopic structure, absence of cleavage and inclusions, moderate hardness and extreme toughness, was selected as the most suitable natural substance for the purpose. It is also cheap and can be obtained easily in this country in homogenous masses.”

This combination of sapphire and agate turned out to be successful and solved the problem.

H H Thomas was also involved in the analysis of concrete from German fortifications.

In September 1917 it was noticed that German concrete pill-boxes on Vimy Ridge, which had been captured by Canadian troops, were made with gravel which could not have come from Belgium. It was suspected that the Germans had transported the gravel through the neutral Netherlands. If this was the case then it was in contravention of the Netherland's neutrality declaration as the Dutch were supposed to prevent the belligerent powers from transporting military materials across neutral territory.

By October samples of the suspect concrete had been received by the Geological Survey and analysed. One of these samples was F2397.      

 Niedermendig lava set in concrete
(F2397)

Photomicrograph of Niedermendig lava (viewed under crossed polars)
(F2397) 

In a report Thomas described it as:

 "Fine grained grey spongy lava. Tephrite. Occurs as angular fragments and chips, and has the appearance of a quarried rock. This rock by its mineral-constitution and structure is of an unmistakable type. It has all the characters of the Niedermendig tephrite, so extensively quarried on the eastern slopes of the Eifel, bordering on the Rhine. Its usual port of Shipment is Andernach" 

Page from report by Thomas (BGS Archives: GSM/PT/A/27)

This meant that the gravel must have come from Germany. This issue was so important the J J H Teall, a former Director of the Geological Survey was brought out of retirement to confirm the identification. 

The evidence resulted in a Dutch threat to stop the transport of German sand and gravel across the Netherlands.
This could have brought the Netherlands into the war but none of those involved wished this so an agreement was reached.

You can find out more about the Geological Survey and the First World War in the paper "Some aspects of the British Geological Survey’s contribution to the war effort at the Western Front, 1914–1918" by D G Bate and A L Morrison. This can be downloaded here

You can read about how one geologist, C B Wedd, was mistaken for a German spy here

You can read more about the forthcoming publication La Terre et le Feu, géologie et géologues sur le front occidental here

Andrew L Morrison