Perhaps the key strength of the Bartholomew Archive is the ability to trace the development of a map from idea to finished product. This can at times afford a unique insight into the motivation, techniques and business practises of one of the world’s foremost cartographic firms. In general, the Bartholomew Archive Printing Record presents a picture of the finished product but at the turn of the 20th century more and more proof and draft maps begin to appear within its volumes.
The map-making process was an exceedingly complex one involving numerous stages, techniques and skills. For those of us who have not trained as map-makers, its processes can be hard to understand. Luckily, a magazine in the Bartholomew Archive called Answers, from 6 October, 1906, has a great description which I shall be heavily quoting from.
According to Answers, having decided upon a map the draughtsmen commence their work with the difficult business of compilation. Compilation involves the decision of what to include and what to omit in each map. Compilation can involve reduction, a process whereby a large map is divided into a vast number of small squares; a smaller sheet is divided up in identical fashion. The draughtsman then copies upon the smaller squares all the details of the larger ones and furthermore, any new information is added thus making the map no mere copy of the original but in fact an entirely new and original one.
When the draughtsmen have done their work, the map passes into the hands of the engraver who has to reproduce it, reversed, on a copper plate. A map measuring about 2ft. square will take a competent engraver four months to engrave. Copper plate engraving is a skill requiring a five year apprenticeship to master. Working in reverse and upside down, each letter of every place name, each line, dot and mark is engraved individually and by hand. These engraved copper plates are never themselves used for printing. A single impression is taken upon a sheet of specially prepared transfer paper. At this stage a patcher adds the finishing touches, borders, scales etc. and this, again, is transferred to the surface of a lithographic stone. Lithographic stones can weigh up to a ton and require delicate manoeuvring onto the bed of the printing machine.
The first stone is used to print the black portions of the map, including outlines, names etc; but where a coloured map is in question, a separate stone has to be prepared for each tint required. Thus at least five separate stones are normally needed to produce a high-class map in colours.
In preparing these stones the utmost care is needed to obtain perfect “register”; that is to say, each colour stone must correspond most accurately in outline with the others. To obtain this register a proof is taken from the black stone and transferred to the tint stones. The portion of the stone not required for each printing is covered in gum, in order to prevent the colour from touching any other portions than those actually required. The selection of colours requires the utmost care and an artistic eye.
Map-printing cannot be rapidly turned out like a newspaper. Each impression has to be taken with care and deliberation, and sufficient time must elapse for one colour to dry before another is printed. In this way the printing alone of a single map can occupy a whole month.
Once the process has been completed the stone is scrubbed and scraped, the impression removed, the surface smoothed and the stone made ready for the next map. But, as Answers does not go on to mention, that is not the end. The maps may require mounting, dissecting, binding and a whole host of finishing touches before it can finally be dispatched. Maps are no longer made in this fashion of course and early Bartholomew maps, for me, are made all the more amazing for the knowledge of the intricate processes that were undertaken in order to bring them to life.