John Hood was born in 1720 at Moyle, co. Carlow. In 1772 he published in Dublin, his 'Tables of Difference of Latitude and Departure for Navigators, Land Surveyors, &c.," in which he recommends that in surveying the bearing of objects should be taken from the meridian of the place. The tables printed in the book are the natural sines of all the angles, in degrees and quarter degrees, to different radii, the latter ranging from 1 to 100, as being best adapted to Gunter's chain. Hood also gives an account of the diurnal variation of the magnetic needle and its correction, and a description of a new surveying instrument. This invention is elsewhere called Hood's compass theodolite, and is described as the basis of the theodolite now used in England and America. He is also said to have anticipated the invention of Hadley's quadrant, but took out no patents. He died about 1783.