Verge escapement be mechanical, depending on which manuscript evidence they regard as conclusive. One candidate is the Dunstable Priory clock in Bedfordshire, England built in 1283, because accounts say it was installed above the rood screen, where it would be difficult to replenish the water needed for a water clock. Another is the clock built at the Palace of the Visconti, Milan, Italy, in 1335. However, there is agreement that mechanical clocks existed by the late 13th century. The earliest description of an escapement, in Richard of Wallingford's 1327 manuscript "Tractatus Horologii Astronomici" on the clock he built at the Abbey of
Controlled-release fertiliser Fertilizers. Controlled-release fertilizer is also known as controlled-availability fertilizer, delayed-release fertilizer, metered-release fertilizer, or slow-acting fertilizer. Controlled-release fertiliser A controlled-release fertiliser (CRF) is a granulated fertiliser that releases nutrients gradually into the soil (i.e., with a controlled release period). The slowness of the release is determined by the low solubility of the chemical compounds in the soil moisture. Since conventional fertilisers are soluble in water, the nutrients can disperse quickly as the fertiliser dissolves. Because controlled-release fertilisers are not water-soluble, their nutrients disperse into the soil more slowly. The fertiliser granules may have an insoluble substrate or a semi-permeable jacket