Grasshopper escapement to Harrison were poor, messy and short-lived. This meant that conventional clocks had to be stopped frequently for cleaning and oiling. Using his clean and absolutely stable grasshopper escapement Harrison began a series of long-term investigations into the performance of clocks, leading to his invention of the gridiron pendulum which counteracted the effects of expansion and contraction with changing temperature. The performance of his improved clocks in turn gave him an accurate, convenient standard against which to test his marine timekeepers. Harrison developed the grasshopper escapement from a conventional anchor escapement which he built for a turret clock to go
Controlled-release fertiliser 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 that prevents dissolution while allowing nutrients to flow outward. The Association of American Plant Food Control