Scientists, astronomers, sailors and the general public have long employed a range of microscopes, telescopes, and other magnifying instruments as diverse as the stargazer’s six-footer and pearl-encrusted opera glasses.

Optical instruments vary hugely in sophistication and therefore in price. The earliest telescopes and microscopes dating from the 18th century or before are now difficult to find and command high prices. However, 19th and early 20thcentury examples of all shapes and sizes are still very collectable, as long as they are in good condition and still in their original case.

PreciousMICROSCOPES

Microscopes used for detailed observation into two distinct groups: simple microsco (commonly known as magnifying glasses), with a single lens, and compound microscopes, which have two or more lenses.

Always check that the instrument is fully functional and optically sound, that the original lacquer on brass surfaces has not been rubbed away (a bright, shiny patina reduces the value considerably), and that all the accessories are present. Microscopes from the 19th century were typically sold in a mahogany chest which also housed tweezers, lenses and eyepieces. Without such accessories, the value can he reduced by over 70 per cent.

Simple microscopes dating from the 18th and l9th centuries are usually small enough to fit into a pocket. Most are quite basic and made of brass (although ivory and fruitwood examples are also found), and have no means (or little means) of focusing on the image or specimen, which was held in place by a spike or pin. An 18th-century simple microscope by a maker such as Edmund Culpeper, still in its shagreen case and complete with accessories, can sell at auction for over £1000. Later examples can be cheaper, however, some fetching as little as £1 00. A fairly common variant is the 18th-century `screw-barrel’ microscope, especially designed for use on field trips. It has a handle at the side of the optical tube. Examples sell for £500-£1 000.

Antique Collection

Precious COMPOUND MICROSCOPES

Compound microscopes are more complex — typically with three lenses in the wooden pasteboard or brass tube. The distance of the lower (`objective’) lens from the object being examined can usually be adjusted for focusing, as can the viewing platform on which the specimen sits. Such microscopes came with several eyepieces and objective lenses.

Most early compound microscopes are based on one of two types, the Culpeper or the Cuff. Culpeper microscopes were produced from the 1720s to the early 19th century. They have an optical tube made of pasteboard or wood, which slides inside a cylindrical support sometimes covered in shagreen and supported on three legs. They came in a pyramid-shaped case with a drawer in the base for eyepieces and objectives. The Culpeper trade card of the 1730s and 40s is printed with a crossed daggers sign, and microscopes with their original card can fetch over £5000. More basic examples sell for £1 000-£1500.

Cuff microscopes 2.-2 completely different. The main tube is attached to a brass side pillar by a bracket, and its accurate focusing system means it is considered the earliest precision microscope, first appearing in the 1740s. Despite their greater accuracy, Cuff microscopes can be cheaper today than Culpepers, as many more were made and have survived. They fetch between £800 and £2000.

Today, some of the highest prices are commanded by instruments made between 1850 and 1900 by London makers: Andrew Ross, Powell & Lealand and Smith & Beck. These have achromatic lenses to overcome distortion. Victorian microscopes are almost always signed, and examples by any of these makers can fetch between £500 and £5000. The rarer binocular microscopes introduced in about 0862 are particularly desirable.

By the turn of the century, the market was dominated by two German manufacturers, Ernst Leitz and Carl Zeiss, who produced a range of relatively inexpensive models for the amateur and professional. Examples can be bought today for £ 00-£500.

Precious TELESCOPES

From the time of their introduction in the early 17th century, telescopes were also made along two distinct lines. The reflecting telescope uses a concave mirror to form the image, and was introduced in the mid- 17th century. Examples from the 18th century sell for £500£3000 today. Most are brass and mounted above a short column on a tripod base.

Refracting telescopes use a series of glass lenses to magnify the image and were introduced as early as 1608, although they did not become popular until the Victorian era, when achromatic lenses overcame the problem of distortion. Most have a brass, pasteboard or wooden tube, and are focused by extending or retracting the eyepiece or the whole tube.

Hand-held telescopes for use on board ship generally have a brass tube, often bound with plaited rope or mahogany, whereas military examples are more often bound in leather. Hand-held telescopes were made in very large numbers, and simple ones can be bought for less than £100. However, if they are signed by a good maker, such as Dolland, Ramsden or Adams, they can fetch as much as £500.

Large floor-standing astronomical telescopes with an equatorial mount (for alignment with the earth’s axis), slow-motion, vertical and horizontal adjustment, and a mahogany tripod can be worth £1000-£2000 today with case and extra eyepieces. Smaller, less powerful instruments on a simple mount and oak tripod can be found for £600-£ 1000. Table-top astronomical telescopes with a 2%-3% in (63-89 mm) diameter objective lens and brass tripod fetch £500-£3000.

Precious OPERA GLASSES AND BINOCULARS

In the 18th and 19th centuries, opera glasses were decorative evening-wear accessories. Less powerful than a proper telescope, they were useful for viewing the action of the opera or play — and other theatregoers. Prices reflect the material used and the quality of engraving or mounting. Luxury models with semiprecious stones can fetch up to £1 000, but run-of-the-mill ivory or mother-of-pearl examples go for as little as £100-£150.

Towards the end of the 19th century, binocular field glasses were introduced. They were issued in their thousands to the forces during the First and Second World Wars. Various designs, usually covered in dark leather, were made in France, Germany and Britain. So many were made that examples in good order can easily be found for under £200.

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