---
type: Object
title: The Saltglass Lens
description: A survey and chart doublet lens sold by the Instrument Works, named for
  the green-edged gleam of its coated surfaces.
tags:
- kelvarra
- the-institute
- instruments
- port-ilvess
- measurement
resource: raw/instrument-works-catalogue-1992.md
aliases:
- Saltglass pattern
timestamp: '2026-07-16T15:03:08Z'
citadel_version: 0.3.0
---

# The Saltglass Lens

The Saltglass Lens is a doublet lens sold by the [Instrument Works](../organizations/instrument-works.md), figured and proved at the Works for survey and chart work; the Works calls it "the pride of the optical bench" and praises its "uncommon flatness of field."[^s1]

## Name

The lens is named for the green-edged gleam of its coated surfaces in a raking light — a colouring the polishing room achieved by accident in the pattern's first series, and has been required to achieve on purpose ever since.[^s2] It is supplied in three survey diameters, in brass cells engraved with the proof date.[^s3]

## Reception and price

The pattern was noticed at flattering length in *The Meridian* — a periodical, not to be confused with the Institute's bronze [Meridian](../objects/the-meridian.md) bearing line at Corran Hill — for its winter number of 1991, and the Works has been catching up with the resulting demand ever since; as of the 1992 catalogue, the wait stands at eight months.[^s4] The smallest diameter is priced at sixty [skells](../concepts/skell.md); the larger two are priced by quotation.[^s5]

## See also
- [Instrument Works](../organizations/instrument-works.md)
- [The Meridian](../objects/the-meridian.md)
- [Skell](../concepts/skell.md)

## Sources
[^s1]: [raw/instrument-works-catalogue-1992.md](../../raw/instrument-works-catalogue-1992.md), lines 23-24 — the doublet lens, its purpose, and the Works' description of it (ingested 2026-07-15)
[^s2]: [raw/instrument-works-catalogue-1992.md](../../raw/instrument-works-catalogue-1992.md), lines 24-27 — the name's origin in the coating's green-edged gleam (ingested 2026-07-15)
[^s3]: [raw/instrument-works-catalogue-1992.md](../../raw/instrument-works-catalogue-1992.md), lines 27-28 — the three survey diameters and engraved brass cells (ingested 2026-07-15)
[^s4]: [raw/instrument-works-catalogue-1992.md](../../raw/instrument-works-catalogue-1992.md), lines 28-30 — the notice in The Meridian's winter 1991 number and the resulting wait (ingested 2026-07-15)
[^s5]: [raw/instrument-works-catalogue-1992.md](../../raw/instrument-works-catalogue-1992.md), line 30 — prices for the three diameters (ingested 2026-07-15)
