The engraving of the July 4, 1868, issue of the Illustrated Times. John Stringfellow’s triplane is suspended on its wire, with a canvas sheet to arrest it in the distance. In the foreground on the left is William Gibson’s “aerial apparatus”. In the background, from left to right, are an assortment of kites, Duncan McPhail’s Aerial Steamship, Kaufmann’s model of his “Airmotive Engine” and George Ansell’s fish-shaped balloon. At bottom right is the car of Henson and Stringfellow’s Ariel model. Both of Stringfellow’s machines are incorrectly shown with shaft drives to their propellers.

Stringfellow’s prizewinning 1 h.p. light steam engine. Somewhat altered by its creator after the 1868 exhibition, it is now preserved at the Smithsonian Institution in the USA, having been bought from Stringfellow’s son in 1889 by Prof Samuel Langley.

Stringfellow’s triplane as it was displayed at the Crystal Palace in 1868. This machine survives, albeit not entirely true to its original form, having been bought from Stringfellow’s son Frederick by Samuel Langley for the Smithsonian Institution. Its engine and boiler are in the Science Museum, London.

An impression of William Gibson's device, comprising two pairs of feathering wings actuated by the arms and legs. Whether the gentleman modelling the apparatus is based on Gibson himself remains unknown!

The tail and wings of trapeze artist Charles Spencer’s Aerial Apparatus. Based on the classic paper dart, the tail, shown here uncovered, was attached to the operator by means of a wickerwork “corset”. The complete apparatus, demonstrated to Dr Abel Hureau de Villeneuve (with unsurprising results), weighed a mere 18lb (8kg).

Spencer also tried - unsuccessfully - to patent this ambitious full-size paper-dart-based “Manumotive Flying Machine” in 1868. It was to be propelled by a “person actuating suitable propeller-fins”. Note the tiny figure with a telescope between the forward fins in this illustration of the machine over the sea, lending a sense of scale.

The French connection - Viscount Gustave de Ponton d’Amecourt’s steam-powered helicopter model, with two pairs of contra-rotating paddles. Its inventor was a friend of Jules Verne, and was reportedly the first to use the term helicopter, in an 1861 patent.

A somewhat fanciful illustration ofJ.M. Kaufmann’s steam-powered Aeromotive Engine in flight over a bucolic lakeland scene. The illustration was probably based on Kaufmann’s ASGB exhibition model of the machine, which had four fixed superposed wings of 16ft (4-9m) span and two large "propulsive wings" of 14ft (2-5m) span.

Kaufmann apparently used the name Aeromotive Engine to refer to the entire machine, but its powerplant, seen here in vertical aspect, was a steam engine with boiler shell and chimney, the latter clearly visible at the top centre in this illustration.