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New optical products, aggressive marketing, disputed advertising claims, optical businesses expanding while others fail: just another week in the optical news, perhaps. Were Optician around in the mid-18th century, it might well have been reporting on all these topics in relation to the scientific instrument-maker and retailer Benjamin Martin.
Martin came from humble stock, born in 1704, the third of six children of a farmer with land near Guildford. Largely self-taught, he became firstly a mathematics teacher, then the proprietor of a boarding school in Chichester, West Sussex. Around 1737 he began to develop an interest in optics and optical instruments. Characteristic of Martin's personality was that he felt he could make improvements to whatever technical subject he turned his mind. Thus experiments resulted in him developing a 'pocket compound microscope' cheaper and more portable than the fashionable 'Culpeper' model. He wrote a monograph describing his new design, including a description also of a 'universal' microscope he had devised. These and other simple optical items he advertised for sale from his home.
By the early 1740s he had swapped teaching for a life of itinerant lecturing on 'Natural and Experimental Philosophy', all the while demonstrating his apparatus and advertising his instruments for sale. While spells in Reading, Bath and Norwich were moderately successful for his lectures, the logistics of getting his optical instruments from the manufacturers to his customers was proving unsatisfactory. In 1756 he decided on moving to London to open his own shop. But to trade in the City required him to be a freeman. The relatively new discipline of instrument-making did not have its own guild (the Worshipful Company of Scientific Instrument Makers was, in fact, only established in 1955, with the support of the Spectacle Makers and Clockmakers) apparently many instrument makers became freemen of the Grocers' Company, although records show that Martin joined the Goldsmiths' Company and became a freeman of the City in February 1756.
Martin found an advantageous site in Fleet Street located just two doors away from the Royal Society's home of the time at Crane Court, so that the Society's members would inevitably pass by his premises on their way to meetings. He began a vigorous campaign of marketing innovative products almost immediately, to the consternation of the many opticians and instrument makers in the neighbourhood. One of these products was his 'visual glasses' (sometimes referred to by modern collectors as 'Martin's Margins'). He promoted them in a pamphlet, An Essay on Visual Glasses (Vulgarly called Spectacles), in which he would show 'From the principles of Optics, and the nature of the Eye, that the common Structure of those Glasses is contrary to the Rules of Art, to the Nature of Things, etc, and very prejudicial to the Eyesand Glasses of a New Construction proposed.'
The visual glasses were designed to overcome the many inherent faults of 'common spectacles' as Martin saw them. These were chiefly that the lenses were placed in the same plane, parallel to the eyes, causing light rays to be refracted irregularly toward the eyes the large lens size admitted too much light to the eyes, causing irregular refraction from the lenses' periphery and also excessive, harmful light, when only a particular quantity of light is necessary for perfect and distinct vision clear glass or the usual shades of coloured glass admitted the larger, red, particles of light which are not as refractable as the smaller, blue particles the image through correctly coloured lenses would be more perfect than clear ones.
Martin introduced three major innovative features to rectify these deficiencies:
? The lenses were tilted inward, so that their optical axes converged on to the object of regard
? The lens apertures were reduced from a typical diameter of 1