The book was found on Wednesday afternoon in a crate marked “Natural History — Miscellaneous,” between a water-damaged atlas of migratory birds and a pamphlet on the cultivation of river oysters. It is a slim volume, octavo, bound in green cloth that has faded to the colour of pond water. The title page reads: The Fauna of the Lower Ashwater: Being an Account of the Animal Life of the River and Its Banks from Millgate Weir to the Harbour Mouth. The author is Clement Birch. The year is 1891.

It is not the book itself that has caused a small commotion among the volunteers at Fowler’s Books — copies of Birch’s Fauna are held by the Polytechnic Library and the Royal Institute, and it is cited regularly in the city’s natural history literature. What has caused the commotion is what Birch wrote in the margins.

Dorothy Cresswell-Hume, the retired librarian organising the cataloguing of Cedric Fowler’s fourteen thousand volumes, noticed the annotations while processing the natural history section on Wednesday. The handwriting — small, precise, slanting slightly to the right — runs throughout the volume, but it is densest in Chapter Seven: “Mammalia of the Estuary and Tidal Flats.”

“I thought it was a reader’s copy at first,” said Mrs Cresswell-Hume, turning pages with the careful hands of a woman who has spent forty years handling books. “Then I realised the annotations were correcting the printed text. Only the author would do that.”

Eight or Ten in Number

Birch’s published account of the harbour seal colony is well known. He documented “a company of harbour seals, eight or ten in number” on the mudflats below what are now Bramblegate Steps, describing them as “well established and evidently resident.” It is the last published record of seals in the lower Ashwater before the colony vanished in the early twentieth century.

The margin annotations expand this account considerably. Beside the published description, Birch has added: “I count them with more confidence after four visits — eight adults certain, two juveniles probable, one of the latter noticeably smaller and less confident in the water. The adults haul out at low tide on the eastern mudflat, where the freshwater spring enters from beneath the wharf.”

The freshwater spring beneath the wharf. Dr Annalise Fenn-Coulthard, who has been studying the current colony of ten harbour seals at precisely the same location, arrived at Fowler’s Books within the hour of being notified.

“The spring,” she said, reading the margin note for the third time. “He saw the spring. That is almost certainly the Lower Conduit outfall — the same freshwater source that appears to be creating the micro-habitat for the current colony.”

Birch could not have known what lay beneath the wharf. The Lower Conduit was unmapped until Pella Strand’s survey this year. But he observed its effect: a localised area of cooler, fresher water that attracted seals to this specific stretch of mudflat, one hundred and thirty-five years ago and again today.

A Folded Map

Tucked between pages 94 and 95 is a folded sheet of cartridge paper bearing a pen-and-ink sketch map of the lower Ashwater from the footbridge to the harbour mouth. Birch has marked the seal haul-out sites with small crosses, the freshwater spring with a circle, and the line of the mudflats at low tide with a dotted border. In the lower right corner, in the same precise hand: “Surveyed October 1891. C.B.”

Strand, who purchased an 1808 brewery district map from Fowler’s shelves last week, has asked to examine the sketch.

“If Birch mapped the spring outfall in 1891, and it matches the conduit terminus I surveyed in February, that is independent confirmation of the system’s continuous function over at least a century and a half,” Strand said. “That strengthens the heritage listing argument considerably.”

Fowler, who has been watching the commotion from his chair near the front window with the expression of a man who always suspected his shop contained more than people realised, offered his assessment: “There are fourteen thousand books in this building. Every one of them knows something.”

The volume has been set aside for professional assessment. Sylvia Hatch, deputy librarian at the Polytechnic, has requested first examination rights. Fenn-Coulthard has requested second.

Mrs Cresswell-Hume has returned to the crate marked “Natural History — Miscellaneous.” She is, she reported, proceeding with somewhat greater care.