Reed water tube boiler straight tubes through which water and steam circulated more freely, it was considered by some contemporary writers on the subject such as Leslie S. Robertson as "behind" in its circulation because of the absence of down-comers. Whereas the Yarrow boilers fitted to the armoured cruiser of 1905 evaporated 11.664 pounds (5.291 kg) of water per pound (454 g) of coal at 100 degrees centigrade (212 degrees Fahrenheit) with natural draught, by the same measure a Reed boiler as fitted to the torpedo boat destroyer of 1896 evaporated 12 pounds (5.44 kg). An advantage of the Yarrow boiler was in weight:
Normal gravity formula equator and lowest the poles. The formulas for calculating the normal gravity is based on the assumption of an imagined rotationally symmetrical ellipsoid model of the earth, the surface of which is identical to an equipotential surface. Consequently this formula depends only on the geographical latitude and the elevation of geographical location. For the normal gravity formula_1 of the sea level ellipsoid, i.e. elevation h = 0, this formula by Somigliana (1929) applies (after Carlo Somigliana (1860–1955)): with Due to numerical issues, the formula is simplified into this: with For the Geodetic Reference System 1980 (GRS 80) the parameters are