Striking large scale three-sheet blue-backed sea chart, published by James Imray & Son and including the orginal brown paste down label for the firm on the verso of the chart. This chart depicts all of the Northern Pacific. There are forty inset maps of islands and harbors, including a massive map of theSandwich Islands (Hawaii), Honoruru (Pearl Harbor), Midway, Bonin, Guajan, Cocos and Socorro Islands. Working sea charts are inherently rare due to the nature of their use aboard ships. Although likely common when first made, the vast majority of them were either destroyed by use or destroyed intentionally when new updated versions were obtained. One of the earliest examples to include the additional insets.. Imray originally was in the stationary and account book publishing business. In 1836 Imray joined with Michael Blachford, a small sea chart publisher based in London. The partnership flourished and soon began to compete with the larger firm of Norie and Wilson. In 1846 Imray bought out Blachford, taking over as sole proprietor. The firm later, led by descendents, survived into the 20th Century. The present example has some very minor dampstaining along the lower part of the map, but is generally in excellent condition for working chart.