One of the most exciting aspects of Charles Darwin's correspondence is the opportunity it gives to researchers to 'get to know' Darwin as an individual. The letters not only reveal the scientific processes behind Darwin's publications, they give insight into his personal life-the world of his family, his circle of friends and his community. This set of resource modules has been designed with the hopes of sharing some of the knowledge gained from our work on Darwin's correspondence with university students.

Darwin became increasingly involved in botanical experiments in the years after the publication of Origin. The building of a small hothouse - a heated greenhouse - early in 1863 greatly increased the range of plants that he could keep for scientific investigations, in particular tropical plants for his experiments into their sensitivity to touch. He was persuaded to build it - an expensive undertaking - by a neighbour's gardener who had been helping Darwin use his employer's hothouses over the previous two years. Darwin enjoyed looking through plant catalogues and making lists of exotic specimens with which to stock the hothouse, and it proved so valuable, and the work so engrossing, that in the end he built a complex of greenhouses capable of sustaining a wide range of species.

Charles and Emma Darwin, with their first two children, settled at Down House in the village of Down (later 'Downe') in Kent, as a young family in 1842. The house came with eighteen acres of land, and a fifteen acre meadow. The village combined the benefits of rural surroundings, where Darwin could make observations and undertake experiments in natural history, with reasonable ease of access to London, and was the environment within which Darwin's work over the last forty years of his life was almost exclusively conducted.

One of the real pleasures afforded in reading Charles Darwin's correspondence is the discovery of areas of research on which he never published, but which interested him deeply. We can gain many insights about Darwin's research methods by following these 'letter trails' and observing how correspondence served as a vital research tool for him.

Darwinian evolution theory fundamentally changed the way we understand the environment and even led to the coining of the word 'ecology'. Darwin was fascinated by bees: he devised experiments to study the comb-building technique of honey bees and used his children to observe the flight paths of bumblebees around their home.

One of the most fascinating aspects of Charles Darwin's correspondence is the extent to which the experiments he performed at his home in Down, in the English county of Kent, seem to prefigure modern scientific work in ecology.

Honeycombs are natural engineering marvels, using the least possible amount of wax to provide the greatest amount of storage space, with the greatest possible structural stability. Darwin recognised that explaining the evolution of the honey-bee's comb-building abilities was essential if his theory of natural selection was to be taken seriously, and in the 1850s he carried out his own experiments at his home at Down House in Kent, and exchanged many letters on the subject. One correspondent even drew an ingenious analogy with a plum pie - you can try this at home!