THIS is one of the interior, as well as one of the original counties of the State, and was first formed in 1675, and its boundaries definitely fixed by the act of January 21, 1709-10, and comprised the teritory then known as Elizabethtown and Newark, and now covered by the counties of Essex, Union, and a part of Middlesex and Morris Counties. Essex County, as now constituted, is bounded on the northeast by Passaic County, east by Bergen and Hudson Counties and Newark Bay, southwest by Union County, and northwest by Morris County.

With the exception of the two trap-ridges crossing the county from northeast to southwest, and known as the First and Second Mountains, the surface is gently undulating, and in some portions quite level, so much so indeed, that it is covered by tide marsh and wet meadow. The principal streams are the Passaic River, which forms the boundary line between this and Morris County, and a portion of the boundary line between this and the counties of Passaic, Bergen, and Hudson ; the east and west branches of the Rahway River, both of which take their rise in Essex County, the first in Orange City and West Orange, and the latter in West Orange, between the two mountains ; the first and second rivers, both flowing northeasterly into the Passaic ; Parrow and Wigwam brooks, the first rising in the city of Orange, and the latter in West Orange, both uniting near the northeast line of the city, forming the head waters of First River. The county is crossed by the Morris and Essex Canal ; the Newark branch of the New York, Lake Erie and Western railroad; the New York and Greenwood Lake railroad, with branch from near North Newark Station to Orange ; the Pennsylvania railroad; the Delaware, Lackawanna and Western railroad, with branch from Newark to Bloomfield and Montclair; the Newark and New York, with branch to Perth Amboy, and street railroads running from Newark to Irvington, South Orange, East Orange, and Orange, Bloomfield, and Belleville.

The area of the county by townships as given by Professor George H. Cook in 1868, was as follows:

Belleville, 5,062 acres; Bloomfield, 8,070 acres; Caldwell, 17,920 acres, 2,617 of which was wet meadow land; Clinton, 5,229 acres; East Orange, 2,394 acres; Fairmount, (now West Orange), 4,621 acres; Livingston, 11,354 acres, 333 acres of which is wet meadow land; Milburn, 6,234 acres ; Newark, 9,126 acres, 4,282 acres of which are tide marsh; Orange, (not in Cook's report) estimated at 1,800 acres ; South Orange, 6,118 acres; West Orange, 3,725 acres. Total, according to Professor Cook, (not including Orange), 79,852 acres. Deducting Fairmount Township, which was not at the date of the report a township, but the name had been changed five years before, to West Orange, and we have a total in county of 77,021 acres, allowing Orange to be 1800 acres.

 In 1790, Essex County, (including portions of what is now Morris, Passaic, and all of Union County,) had gone up to 17,785. In 1800, it was 22,269 ; 1810, 22,984; 1820, it was 30,793; in 1830, it had risen to 41,- 911 ; 1840, after setting off a part of Passaic in 1837, the population was left at 44,621 ; in 1850, it was 73,950. Again, March 19, 1857, the area of the county was reduced by the formation of Union County, yet in 1860, the population had increased to 98,877, and at the close of the war in 1865, it had mounted up to 124,441, and in 1870, it was 143,839. In 1880, the county showed by cities and townships, the following population: Newark, 136,508; Orange City, 13,207; Belleville, 3,004; Bloomfield, 5,748; Caldwell, 3,167; Clinton, including Irvington, 2,742; East Orange, 8,349; Franklin, 1,617; Livingston, 1,401; Milburn, 1,743; Montclair, 5,147; South Orange, 3,911; West Orange, 3,385. Total, 189,929.

Governors of New Jersey.-Chronological List.