So I saw, in real dollars, the cost of computer memory fall to one one-**millionth** of what it was thirty years ago.

The imperfections of the thermopile, with which he began his work, led him, about 1880, to the invention of the bolometer, an instrument of extraordinary delicacy, which in its most refined form is believed to be capable of detecting a change of temperature amounting to less than one-hundred-**millionth** of a degree Centigrade.

The small ratio, or ratiuncula, is in fact that of the **millionth** root of to to unity, and if we denote it by the ratio of a to 1, then the ratio of 2 to I will be nearly the same as that of a301'°30 to i, and so on; or, in other words, if a denotes the **millionth** root of 10, then 2 will be nearly equal to a 301,030, 3 will be nearly equal to a477,1u, and so on.

It is easy to calculate that this would be produced by an annual fall of matter equal to one nineteen **millionth** of the sun's mass, which would make an envelope eight metres thick, at the sun's mean density; this would be collected during the year from a spherical space extending beyond the orbit of Jupiter.

When constructed for purposes of extreme accuracy they will turn with the one-**millionth** part of the load weighed, though to ensure such a result the knife-edges and their bearings must be extremely hard (either hardened steel or agate) and worked up with great care.

Landolt and others, made it at first appear that the change in weight, if there is any, consequent on a chemical change can rarely exceed one-**millionth** of the weight of the reacting substances, and that it must often be much less.

It appears tolerably safe to conclude that, whatever errors 'may have affected the determination, the diameter or distance of the particles of water is between the two thousand and the ten thousand **millionth** of an inch " (= between 125 X I o 8 and 025 X 10 -8 cms.).