Beyond the introduction of the spider line it is unnecessary to mention the various steps by which the Gascoigne micrometer assumed the modern forms now in use, or to describe in detail the suggestions of Hooke, 4 Wren, Smeaton, Cassini, Bradley, Maskelyne, Herschel, Arago, Pearson, Bessel, Struve, Dawes, &c., or the successive productions of the great artists Ramsden, Troughton, Fraunhofer, Ertel, Simms, Cooke, Grubb, Clarke and Repsold.
Under the Dawes Allotment Act of February 1887, and a special statute of March 1889, an agreement was made with some Indians, and about 11,000,000 acres, or about half of the reserve, was thrown open to settlement on the 10th of February 1890.
Although the British had tried to keep this movement a secret, Dr Joseph Warren discovered their plans and sent out Paul Revere and William Dawes to give warning of their approach.
To avoid such error Dawes used double wires, not spider webs, placing the image of the star symmetrically between these wires, as in fig.
Dawes, who employed a micrometer of the English type (figs.