Experimental engineer. The son of a Dundee merchant, Kirkaldy was educated in the city and then Merchiston Castle School in Edinburgh. He also attended lectures at the University of Edinburgh. He returned to Dundee to join his father's business, but not finding this work challenging, he took an engineering apprenticeship at Vulcan Foundry in Glasgow, where in Robert Napier made steam-engines for his ships. Kirkaldy began testing materials in the 1850s and left Napier's employment in 1861 to design a universal testing machine which he set up in a workshop in Southwark (London). He was awarded a Gold Medal by the Institution of Engineers in Scotland in 1864. From 1866, he offered one of the earliest services to provide advice to engineers on the strength and robustness of metals such as iron and steel. Kirkaldy extended his service by developing methods for examining the microstructure of metals to determine flaws and the effects of hardening. He was able to suggest many improvements to bolts, bridge-link eyes, tie-rod ends, the shape of railway axles, gears and engines, together with advancing processes such as riveting and welding.
Notably, Kirkaldy was retained by the Court of Inquiry into the Tay Bridge Disaster to test components of the bridge and determine why it had failed in 1879. He was able to conclude that the cast-iron lugs which retained strengthening tie-bars had been used inappropriately because they were very weak under tension.
He was awarded the Freedom of the City of London in 1888 in recognition of this work.
His testing works in London is now the Kirkaldy Testing Museum, where his universal testing machine can still be seen operating.
