Mole draining or its equivalent has been practised on clay land for many years; indeed, according to Richardson and Fussell, writing in the Journal of the Ministry of Agriculture, 1922, a patent for a mole plough was taken out in England in 1797. Fowler's mole plough appeared about 1850, and since then this type of implement, drawn by steam engines, has played an important and valuable part in the farming of the heavy arable areas of the eastern counties. Dr R. McG. Carslaw and Mr A. W. Menzies-Kitchin have recently (1933) collected much useful information on mole draining practice in East Anglia. The data were obtained from some 80 farms, and are summarised in Report No. 21 of the Farm Economics Branch of the Cambridge University Department of Agriculture. Dealing with the mechanical side of the subject, the Report states “ …it was rather surprising to find that tractors had been used for draining only on 3 out of 75 farms, and that on two of these, steam engines had also been employed. On one farm…a team of 10 horses, and on two others, oil engines…On the remaining farms, representing 95% of the total, power was supplied by steam engines.” In respect of the durability of mole drains the Report states “The data showed considerable variation in the length of life of mole drains, but the average life appeared to lie round about 13 years, with an average range of from 8 to 19 years… Silting, stated generally to be caused by the presence of loose sand and/or gravel in the clay subsoil, was the most common cause of failure.”