In 1882-4, Frances Groome's Ordnance Gazetteer of Scotland described Cromartyshire like this:
Cromartyshire, a county, interlaced with Ross-shire, in the N of Scotland. It comprehends an ancient sheriffdom, hereditary in the family of Urquhart of Cromarty, and detached districts annexed in the latter part of the 17th century, at the instance of Viscount Tarbat, afterwards Earl of Cromarty. The ancient sheriffdom, or old shire, comprises Cromarty parish, the greater part of Resolis parish, and an undefined portion of the Mullbuy; and is usually stated to have a length of about 16 miles, a breadth of about 6½ or 7 miles, and an area of about 39, 690 acres. ...
The detached districts are a district surrounding Tarbat House, on the NE seaboard of Cromarty Firth; a district commencing on the Dornoch Firth a little E of Tain, and extending eastward to the Moray Firth in the vicinity of Geanis; two small tracts in Kincardine parish, adjacent to the river Carron; a district extending west-north-westward from the vicinity of Dingwall, and including Castle-Leod and part of Ben Wyvis; two tracts on the N of respectively Loch Fannich and Loch Nid; a tract along the S side of the middle and upper parts of Little Loch Broom; the large district of Coigach, lying between Loch Broom and Sutherland, and extending to Loch Enard and Rhu More promontory; and the Summer islands, lying in the N side of the mouth of Loch Broom. These eight are estimated to measure aggregately about 344 square miles, or 220,586 acres. The ancient valuation of the property was £12,896; but the modern valuation of the property, and all the other modern statistics, are merged into those of Ross-shire. The county has a court of lieutenancy of its own; but it has no sheriff or even sheriff-substitute of its own; and, as to its fiscal affairs, its parliamentary representation, and even its parochial distribution and its territorial character, with the exception only of Cromarty parish, it is always practically treated as simply a component part of Ross-shire.
Cromartyshire consisted of many separate portions scattered across Ross-shire. For now we give it a location just inland of the town of Cromarty.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Cromartyshire has changed, please see our redistricted information for the modern district of Highland. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Cromartyshire and units named after it.
GB Historical GIS / University of Portsmouth, History of Cromartyshire, in Highland and Scotland | Map and description, A Vision of Britain through Time.
Date accessed: 28th October 2016
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Cromartyshire".