Peter Bower’s vast knowledge of paper obviously includes watermarks; his opinion of those we have found is that A Pirie 8t Sons and Joynson Superfine “would not have been the commonest paper.” But the watermarks were not necessarily uncommon in the late nineteenth century. Monckton’s Superfine was a rarer watermark and Monckton’s also manufactured artists’ drawing and watercolor paper.
Matching watermarks do not necessarily mean the paper was from the same batch, and almost none of the Sickert letters or Sickert/Ripper letters are from the same batch, says Peter Bower, who spent days going through Sickert and Ripper archives and measuring the paper using a 3 Ox lens to study the measurements, fiber content, and distances between chain lines. When paper is manufactured by machine, as A Pirie and Joynson and Monckton’s were, the paper comes from one batch, meaning it is from the same roll. Another batch with the same watermark and a fiber content that is relatively the same may have slight differences in measurements of the sheets of paper due to the speed of drying or the way the machine cut it.
These characteristics – measurements and spacing between the wire the paper was formed on – are the paper’s Y profile, and matching Y profiles mean the paper came from the same batch. Bower says it is not unusual for an individual to have stationery that comes from many batches, and that even when the paper is ordered from the stationer, there could be different batches mixed in, although the watermarks and embossing or engraving are the same. The discrepancies in the Sickert and Ripper letters pertain to their measurements. For example, the “Dear Openshaw” letter with the A Pirie watermark is from the same batch as the November 22nd A Pirie Ripper letter mailed from London, but not from the same batch as the other November 22nd A Pirie letter supposedly mailed from Manchester. Clearly, the Ripper had a mixture of A Pirie batches when he wrote these November 22nd letters, unless one wishes to make the case that there were two different individuals who just happened to write Ripper letters on A Pirie 8c Sons paper of the same type and color on November 22nd.
Differences in measurements can, in some instances, be attributed to conservation. When paper is heated by applying a protective membrane, for example, the paper shrinks slightly. More probable is that the differences in measurements can be explained by reorders from the stationer. During the late 1880s, personalized stationery was usually ordered in a quire, or twenty-four sheets, including unprinted second sheets. A reorder of the same personalized stationery on the same type of paper with the same watermark could quite easily come from a different batch. Or perhaps the stationer used a different standard size, such as Post quarto, which was approximately seven by nine inches, or Commercial Note, which was eight by five inches, or Octavo Note, which was nominally seven by four-and-a-half inches.
An example of a discrepancy in paper size is a Ripper letter with a Joynson Superfine watermark that was sent to the City of London Police. The torn half of the folded stationery measures 6% inches by 9%o inches. Another Ripper letter on the same type of paper with the same watermark was sent to the Metropolitan Police and that stationery is Commercial Note, or eight by five inches. A Sickert letter written on Monckton’s Superfine that we examined in Glasgow measures seven and one-eighth inches by nine inches, while a Ripper letter sent to the City of London Police on the same type of paper with a matching Monckton’s Superfine watermark measures seven and one-eighth inches by eight and nine-tenths. Most likely, this suggests the Monckton’s Superfine stationery is from different batches, but this by no means indicates it was from different Ripper letter-writers.
I point out these different paper batches only because a defense attorney would. In fact, paper of the same type and watermark but from different batches doesn’t necessarily mean a setback in a case and, as Bower pointed out, having studied other artists’ paper, he “would expect to find variations like this.” Bower also discovered paper in Ripper letters that did not have variations, and because they also had no watermarks, these letters were not really noticed by anyone else. Two Ripper letters written to the Metropolitan Police and one Ripper letter written to the City of London Police are on matching very cheap pale blue paper – and for three letters to come from the same batch of paper strongly indicates that the same person wrote them, just as matching watermarks, especially three different types of matching watermarks, are hard to dismiss as coincidence.