The Grubbs: 19th-century Irish stargazers

I always associate stargazing with summer, when we were allowed to stay up late while vacationing far enough away from city lights to get a good view of a meteor shower. In fact, winter is a much better time of year to see celestial objects.

Still, if you can manage to stay up until it is fully dark, you might catch the Delta Aquariads meteor shower this month. If you do, you will be joining a long history of stargazing and amateur astronomy. Both of these activities experienced a heyday during the 19th century as the technical skills needed to produce large lenses and mirrors, and thus larger telescopes, improved dramatically.

The Grubb family were among the most talented innovators. Their telescope and instrument factory was based in Dublin, but they contributed to telescopes in India, Australia, South Africa and the Crimea as well as Greenwich and Dublin.

Astronomy in the early 19th century was dominated by the gentleman amateur. Thomas Grubb’s apparent lack of formal education did not prevent him from tinkering with telescopes and becoming an astronomical observer himself. He probably gained knowledge of engineering and instrument-making through experience. His early business made not only telescopes but parts for billiard tables. Thomas eventually entered into a correspondence with Ireland’s premier astronomer at the time, Thomas Romney Robinson, who was director of Armagh Observatory. Robinson assisted Thomas in gaining early commissions, including modifications to Lord Rosse’s Leviathan telescope at Parsonstown.

Thomas’s son, Howard Grubb (1844-1931), was sent to Trinity College for an academic version of engineering. However, he was withdrawn to assist his father in casting a 4ft mirror for the Great Melbourne telescope and did not return. That telescope was the making of the Grubb enterprise, and the commission was one example of a shift towards government-sponsored observatories and away from the gentleman amateur.

Astronomical growth

Another major change over the lifetime of the Grubbs’ business was the great expansion of the British empire and the involvement of Irish men and women in it. As European empires grew, so too did the territories open to scientific endeavour.

Astronomers became part of the network of imperial scientists, and astronomical observatories sprung up across European colonial territories.

Of particular interest was astronomical observation in the southern hemisphere. As explorers and colonisers were filling in the terrestrial map, astronomers sought to do the same with the celestial one. Southern hemisphere telescopes could see parts of the sky that those in the northern hemisphere could not.

In 1887, an international congress of astronomers representing 19 countries took advantage of this network to begin an ambitious project. They proposed a photographic “Map of the Sky”, with photographs taken through specially designed telescopes. Each observatory was assigned a specific portion of the sky to photograph. The Grubbs created “astrographic” telescopes for several of the observatories, but the project was not completed until 1964.

Scientific astronomy now benefits from different ways of visualising the cosmos, including radio waves. Nonetheless, huge mirrors and large telescopes remain important. In 2014, construction began on the European Extremely Large Telescope at the European Southern Observatory in Chile. The name basically says it all: instead of a Grubbs 4ft-6ft mirror, this telescope will have a mirror of 39m in diameter. No one has found a way to cast (or indeed transport) a mirror of this size. Instead it will be composed of almost 800 smaller hexagonal mirrors.

Howard Grubb continued to produce instruments, including submarine periscopes, throughout the first World War. Soon after the war he left the business, but the name continued in the firm of Grubb-Parsons, which made telescopes until its closure in 1985.

• Tribute: I would like to dedicate this column to the memory of Ian Elliott, a solar physicist at Dunsink Observatory and historian, who died in May. Ian was a frequent contributor to conferences and publications on the history of Irish science. This article draws on Ian Elliott's Grubbs of Dublin: Telescope Makers to the World in J Adelman and E Agnew (eds), Science and Technology in Nineteenth-Century Ireland (2011).

Juliana Adelman lectures in history at St Patrick’s College Drumcondra