[ New Hampshire ]: New England Telephone and Telegraph Company 1925. First Edition. 9 x 11 1/2 inches. Thick boards covered in grey coated linen. Bulks 2 1/2 inches thick at the spine. Bound in boards secured by two screw posts. An archive of more than one hundred 7 1/2 x 11 inch photographs each mounted on linen. Tonality of the images is excellent. The front cover is stamped "Outside Plant - General Store and Garage Equipment - General Tools and Implements as Included in Inventory and Appraisal of Property New England Telephone and Telegraph Company State of New Hampshire as of April 1, 1925"
The photographs are divided into sections, each under a different tab. Each section of photographs is preceded with a financial page noting the value of the infrastructure being documented. A sample section is "Exchange Pole Lines Summary - Reproduction Cost - Fully Owned and Jointly Owned". Most photographs have typed explanations at bottom. Other section headings are Pole Lines, Exchange Poles, Toll Poles, Aerial Cable, Exchange Aerial Cable, Toll Aerial Cable, Exch. Aerial Wire, Toll Aerial Wire, UG Conduit, UG Cable, Exch UG Cable, Toll UG Cable, Motor Vehicles (this section empty), Other Accounts, Submarine Cable, GNL Tools and Implements. Very Good. Boards. 
The first category tab has a stamp "Exhibit No 14 New England Tel & Tel Co, New Hampshire P.S.C. No D. 964 Witness GK Manson". A legal expert advised us that this archive was probably 'an exhibit compiled for use in a state rate case - a substantial portion of which consisted of proving that the physical plant included in the company's 'rate base' [on which it was allowed to earn its 'fair return'] was 'used and useful' and fairly valued.' In other words, NE Telephone was attempting to prove that the rates it charged to customers were fair and appropriate based in part on the inventory and property documented here.
A fascinating view into the state of the art in telephone/telegraph cabling and outside plant as well as how that infrastructure was used to justify rates in 1925. Archives of this nature are certainly scarce on the market, and worthy of study and preservation. While individual photographs are found occasionally, groupings like this which tell a story larger than the sum of their parts are quite uncommon.
Major Mason organized the 401st Telegraph Battalion from the NE Tel and Telegraph Company and was involved in analysis of the Transatlantic Cable (see Circuits of Victory by Lavine).