By the 1850's, the science and technology of artillery had advanced, meaning that brick-built fortfications that stood high above the ground were fast becoming as vulnerable to modern guns as the curtain walls of medieval castles became to the advent of the cannon and gunpowder. In 1854, Sir William Armstrong had come forward with proposals for a new rifled breech-loading gun, which involved the use of new manufacturing techniques and principles. Many tests were performed to assess Armstrong guns of various types, one of which took place on August 7-8, 1860. The nature of the test was to see how rapidly a battery of three guns could make an impression on the walls of Tower 71, which, whilst not only of inferior fortification design at that time, was also having its foundations exposed by the tide, making its demise inevitable.
The following sequence of photographs were taken as the trial commenced, and are quite rare, given the relative infancy of photography at that time. Each view was actually photographed twice - the second from a slightly different perspective, so that each pair could be mounted on a card slide to be placed into a special viewer. The eyes and brain merge the two images together, to produce a three-dimensional image. The 3-D principle has been popular ever since, and at that time was probably the sort of thing on which after-dinner conversation for discerning Victorian Gentlemen was based.
It is not known who took the photographs, but in the The Times of August 9, 1860, it is said that "The Duke of Cambridge and a brilliant staff of artillery and other officers were present on the occasion, furnished with a telegraphic and photographic apparatus, which were in constant use." It is unlikely that there were many cameras present, such was the art of the photographer at this early point in the history of photography. Each photo has a handwritten caption on the reverse, which might have been written by somebody who witnessed the experiment, and purchased the photographs at a later date, as a couple of small mistakes appear in the captions. The original captions are given throughout, including the errors. It is interesting to note that the War Department appear to have used line drawings instead of photographs to describe the effects of the guns.Compare these photos with the six views reproduced on page 42 of Bill Clements' book, 'Towers of Strength' and it will be seen that some are very similar, so it is probable that these drawings were produced from similar photographs after the event. Any reference made to a 'view'refers to these drawings.