---
type: Project
title: Brann Tidal Survey
description: The Institute's nine-station tidal gauge survey around the Kelvarra archipelago,
  reporting its 35th season in 1987.
tags:
- kelvarra
- the-institute
- tidal-survey
- measurement
- port-ilvess
resource: raw/brann-tidal-survey-1987.md
aliases:
- BTS
timestamp: '2026-07-16T15:03:08Z'
citadel_version: 0.3.0
---

# Brann Tidal Survey

The Brann Tidal Survey (BTS) is [The Institute](../organizations/the-institute.md)'s tidal gauge survey, run from nine stations around the Republic of Kelvarra's archipelago.[^s3] Its report for the 1987 season records the Survey's thirty-fifth consecutive season, with all nine stations reporting and no loss of record at any of them — a result the Survey says it does not take for granted, given the weather.[^s2] The season opened with the proving of the gauges in April and closed with the equinoctial series in late September.[^s2] The report was prepared at the [Old Customs House](../misc/old-customs-house.md), [Port Ilvess](../misc/port-ilvess.md), for the Council of the Institute, and submitted there on 30 October 1987.[^s1][^s9]

## Stations and calibration

The nine stations stand as: three about the harbour and roads of Port Ilvess; two on the west coast of Ilvess, at Corrie Ness and the Long Skerry; two on Sarn, at Sarnholt and the Hot Spring landing; one on [Little Moriny](../misc/little-moriny.md), at the light; and the outer station on the Fell Rocks, which the Survey calls the most expensive item in its budget per foot of paper it produces.[^s3] Every gauge is proved each April against the Survey's travelling standard, and the travelling standard is in turn proved against the KSB before it leaves the Institute's building and again on its return; report pressures are reduced against the KSB series, and heights are given on the Survey datum of 1953.[^s3]

## The 1987 season

The tidal year was unremarkable in range and remarkable in temper: the spring series ran close to prediction all season, seldom off by more than a hand's breadth at any harbour station.[^s4] The equinoctial gales, by contrast, drove two storm surges through the roads in September; the greater of the two put the fish market arcades under water for four hours and put the Survey's own seawall predictions under review for rather longer.[^s4] The surge sheets were copied to the harbour board along with the Survey's renewed recommendation on the height of the north quay — a recommendation the board has now declined, with unfailing courtesy, for eleven consecutive years.[^s4]

## The harbour tide clock

The harbour tide clock — [Tomas Ferrick](../persons/tomas-ferrick.md)'s, "as the whole Republic knows" — was proved daily against the transit series through the whole season and kept its rate within four seconds in the month, a performance the Survey says no instrument of its kind on the mainland approaches.[^s5] It did so through a summer in which its tower was twice struck by gulls "of unusual conviction" and once, during the September surge, by a fish.[^s5] The Survey's only standing complaint against the clock is that it makes the rest of the season's instruments look idle.[^s5]

Ferrick's own workshop day-book records that the clock's tidal gearing was cut, in June 1962, directly to the Survey's arithmetic — "I trust it as I trust the tide itself, but cutting a wheel to it is another church" — with fourteen leaves recut where the tooth count and his temper disagreed.[^s10]

## The levelling party and Mount Sarn

The levelling party had a season of unusual interest: extending the datum inland for the harbour board's drainage scheme, it carried the levels up the Sarnholt track and closed its triangle on the summit of [Mount Sarn](../misc/mount-sarn.md), placing the summit at 2,315 metres above the Survey datum.[^s6] The Survey reports the computation checked twice and the field books clean, and notes that the theodolite was proved on the transit pillar before and after the season, observing only that "mountains do not read almanacs" (see [Mount Sarn](../misc/mount-sarn.md) for the Almanac's differing figure).[^s6]

## Staff

The Survey records the retirement of Mrs H. Corliss after twenty-two seasons at the [Little Moriny](../misc/little-moriny.md) station, whose sheets it calls the cleanest it has ever received, and whose tea, it says, was the reason the proving party always began its rounds in the north; her granddaughter takes up the station book with the new season.[^s7]

## Proposals for the coming year

For the coming year the Survey proposes no change of station and one change of method — converting the Fell Rocks gauge to the sealed recording pattern, if the Institute's [Instrument Works](../organizations/instrument-works.md) can spare one before the autumn — plus its customary request to the Council for a second computer, meaning, as it has every year since the request was first entered, a person who computes.[^s8]

## See also
- [The Institute](../organizations/the-institute.md)
- [Port Ilvess](../misc/port-ilvess.md)
- [Old Customs House](../misc/old-customs-house.md)
- [Little Moriny](../misc/little-moriny.md)
- [Mount Sarn](../misc/mount-sarn.md)
- [Tomas Ferrick](../persons/tomas-ferrick.md)
- [Instrument Works](../organizations/instrument-works.md)

## Sources
[^s1]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 3-4 — the report prepared at the Old Customs House for the Council of the Institute (ingested 2026-07-04)
[^s2]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 6-10 — the 1987 season as the 35th consecutive season, all nine stations reporting (ingested 2026-07-04)
[^s3]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 12-19 — the nine stations and gauge/standard calibration (ingested 2026-07-04)
[^s4]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 21-28 — the 1987 tidal year, the September storm surges, and the north quay recommendation (ingested 2026-07-04)
[^s5]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 30-36 — the harbour tide clock's 1987 performance (ingested 2026-07-04)
[^s6]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 38-44 — the levelling party's survey of Mount Sarn (ingested 2026-07-04)
[^s7]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 46-49 — the retirement of Mrs H. Corliss (ingested 2026-07-04)
[^s8]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), lines 51-55 — proposals for the coming season (ingested 2026-07-04)
[^s9]: [raw/brann-tidal-survey-1987.md](../../raw/brann-tidal-survey-1987.md), line 57 — the report's submission date (ingested 2026-07-04)
[^s10]: [raw/ferrick-workshop-notes.md](../../raw/ferrick-workshop-notes.md), lines 37-40 — cutting the clock's tidal gearing to the Survey's arithmetic, 23 June 1962 (ingested 2026-07-04)
