I CANNOT suppose that the mathematicians are all in error; but venture modestly to ask what are the assumed conditions under which a girdle round the earth at the equator would be subject to strain. If the surface of our globe at the equator were continuous and level land, about 30,000,000 of persons—more than 1000 to a mile—standing at equal distances and joining hands, would form a girdle without any strain, or the girdle might be formed of separate pieces of wire placed end to end in close contact, which, if afterwards soldered, would form a girdle, without strain.