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:
Water distribution on Earth a globally significant amount of water. "Saline" groundwater is seldom considered except when evaluating water quality in arid regions. The remainder of the Earth's water constitutes the planet's "fresh water" resource. Typically, fresh water is defined as water with a salinity of "less than 1 percent that of the oceans" - i.e. below around 0.35‰. Water with a salinity between this level and 1‰ is typically referred to as "marginal water" because it is marginal for many uses by humans and animals. The ratio of salt water to fresh water on Earth is around 40 to 1. The planet's fresh