H. Stroud, BA, D.Sc.

Professor of Physics 1887-1926

Professor Stroud had a brilliant career at the University of London, where he gained a first class both in Physics and in Chemistry, and later his D.Sc., and also at Cambridge, where he was eighth Wrangler, (Clare College, Cambridge? Bracketed with Mr. CM Jessop, Fellow) and took a first class in the Second Part of the Natural Science Tripos. He became Lecturer in Physics in 1886, and Professor in 1887. He resigned in 1926.

Notable amongst Stroud’s work was his collaborative work with Lord Armstrong on the nature of electricity. Lord Armstrong had conducted experiments on electric discharges, which led him to suppose the existence of two electric fluids in air and water (these days we should say positively and negatively charged particles) under the influence of violent discharge conditions. At Armstrong’s request Stroud completed his researches, and they were published as a Supplement to Electric Movement in Air and Water with Theoretical Inferences by Lord Armstrong, C.B., F.R.S.. (Newcastle University has a copy of this beautiful book, shelved at Folio 537 ARM).

The phenomena produced by the electrical discharges are quite beautiful. Following is a selection of plates, and the descriptions of their content and method of production.

Plate 9 shows the effect of intercepting an electric discharge between two plates (+ve above and -ve below) by interposing a plate covered in dust) "The result shows a multiplicity of impacts like large and small raindrops. Every impact exhibits an outside radiating ring with a dark spot of dust in the centre...By reversing the current and using a fresh dust plate we get a picture (Plate 10) of the negative action, showing fewer and larger impacts than are seen in No. 9..."

"now come to another mode of illustration, in which a photographic plate is substituted for a dust plate, and in which the luminosity of the discharge produces its own picture when taken in a perfectly darkened room." "I shall begin with a representation of a beautiful luminous star (Plate 12), produced by a sincle powerful discharge delivered from the pair of 10-gallon condenser jars of my Whimshurst machine. The discharge is positive, and is taken from a metallic disc resting on an insulated photographic plate."

During his time as head of the Physics department Professor Stroud expanded the department considerably: at his appointment there was one professor, one lecturer, and seventy-six day students in Physics; at his retirement there were two professors, four lecturers, two demonstrators, and 244 students. The Henry Clifford Stroud prize for Physics (the 'Stroud Laboratory prize') commemorates his son, who was killed in action in 1918.

Sources

C.E. Whiting, The University of Durham 1832-1932,  The Sheldon Press, London, 1932

Lord Armstrong, G.B., F.R.S., Electric Movement in Air and Water with Theoretical Inferences, 2nd edition with a supplement, London (1899),  Smith, Elder and Company.