The question of cost is one of very great difficulty; in all probability no two firms will agree in their quotations for different kinds of work, and the reason for this lies in the large number of factors involved, many of which are very difficult to compute exactly. With respect to line engravings, etching, mezzotint, wood cuts and wood engravings, it is impossible to give any idea of the cost. It depends entirely on the complexity of the subject and the artist employed. As regards lithographic processes for reproduction in one colour the cost varies with the nature of the work. If an artist be commissioned to make an autolithograph, the fee would be agreed upon beforehand. Photolithography and collotype, on the other hand, are processes which do not require the hand of an artist, and these methods of reproduction are relatively inexpensive. The price quoted by the lithographer or collotyper is for printing so many copies, hence the relative cost per copy depends upon the run and on the quality of the paper used. Lithography is cheaper than collotype; but if several illustrations are sent at the same time to be reproduced by collotype, the cost for each would be less than if sent separately. In chromolithography a separate stone is necessary for each colour, hence the cost depends upon the number of stones used, and as several may be necessary to obtain a first-rate reproduction, it is obvious that the process may prove very expensive. Turning to photomechanical processes, the prices vary according to the grade of work required--the best possible, good, and, lastly, cheap work. By best possible is meant the best that can be made under existing conditions, the price being immaterial; in good work the cost will be a limiting but not a preponderating factor, hence the work will be open to criticism; finally, in cheap work, the price is all important, so that the result is a block or a plate which will print well but which must not be criticized as regards its being a faithful reproduction of the original. It is obvious that in the last two cases the quality of the work will depend upon the agreed price, whilst in the first case the cost will depend on the amount of time and skill required. It is obvious, therefore, that a comparison of cost cannot be made between these grades; it is, however, possible to draw up a scale of relative cost of the processes under consideration for work of the same grade. In the table given below, A represents the best possible work, B indicates good work, and C stands for cheap work. Since the line block is the least expensive it is taken as the unit of price; that is to say, if a line block costs 3d. per square inch the cost of half tone, three colour half tone and photogravure would be 7-1/4d., 3s., and 1s. 2-1/2d. respectively.