Dictionary of National Biography, 1885-1900/Lister, Joseph Jackson

LISTER, JOSEPH JACKSON (1786–1869), discoverer of the principle upon which the modern microscope is constructed, born in London on 11 Jan. 1786, was son of John Lister of Stoke Newington, a wine merchant, and his wife, Mary Jackson. His parents were members of the Society of Friends. At fourteen years of age he left school to assist his father in the wine trade; but though for many years closely occupied in business, he contrived by early rising and otherwise to largely supplement the education he had received at school, and was as regards his mathematical knowledge a self-taught man.

His predilection for optics manifested itself early. When a child he enjoyed looking at the prospect through air-bubbles in the window-pane, which improved the vision of his then myopic eye, and enabled him to see distant objects with distinctness. This fact afterwards led him to think it probable that in very young children the eye is generally myopic. At school he alone of all the boys possessed a telescope.

The achromatic microscope was early an object of interest to him; but it was not till 1824, when he was thirty-eight years old, that he did anything to improve the object-glass. His first work of this kind is recorded in a note in the possession of the author of this memoir, dated 1825, to the following effect: ‘The 4/10 and 2/10 achromatic object-glasses, made by W. Tulley at Dr. Goring's suggestion, delighted me by their beautiful performance, but they appeared to me to have a great disadvantage in consequence of the thickness in proportion to their focal length, which W. T. thought could not be avoided. I therefore induced him to make for me one of 9/10, much thinner in proportion, and had the satisfaction to find its performance very nearly equal to his best 2/10. In one respect, indeed, it is superior; showing when in good adjustment the reflection from a minute ball of mercury a bright point in any part of the field, while in the 2/10 and 4/10 it is so shown only in a small portion of the field near the centre, and in the rest has a bur shooting outwards.’ This bur, of which a sketch is given, is the first mention of the ‘coma,’ which afterwards formed so important a subject of his investigations. The note goes on to describe a suggestion for another combination, illustrated by drawings of magnified views of the curves of the glasses, executed with his usual extreme neatness and accuracy; and it concludes with the words: ‘tried many experiments to ascertain the best means of correcting small errors in aberration.’ This note is the first of a long series of accounts of experiments, with remarks upon them. The notes are beautifully arranged, and are well fitted for publication.

In 1826 Lister gave Tulley further projections of object-glasses, and made a sketch for the engraver to illustrate a description of Tulley's microscope, which that optician published, with a fitting acknowledgment of his indebtedness to Lister's ingenuity and skill. Besides the improved object-glasses, Lister designed for this instrument a graduated lengthening tube to the body, the stage-fitting for clamping and rotating the object, a subsidiary stage, a dark well, a large disc, which would incline and rotate for opaque objects, a ground-glass moderator, a glass trough, a live-box made with flat plate, a combination of lenses to act as condenser under the object (apparently the first approach to the present achromatic condenser), the erecting-glass, and the adaptation of Wollaston's camera lucida to the eye-piece. The value of the erecting-glass for facilitating dissections under low powers is perhaps even yet not sufficiently appreciated. The camera lucida had long been a favourite instrument with Lister for drawing landscapes, and the tripod which he invented for supporting the drawing and the camera is that which is now universally used by photographers.

In December 1826 Lister's notes supply an account of an examination of a set of four plano-convex lenses, each consisting of a biconvex of plate-glass and a plano-concave of flint-glass cemented to it by varnish, constructed by Chevalier of Paris. Here Lister records for the first time some puzzling appearances in combinations of compound lenses, which ultimately led him to his great discovery of the two aplanatic foci. Each of Chevalier's compound plano-convex lenses when used singly presented a bur or coma outwards, but when two of them are combined this coma, instead of being exaggerated, as might have been expected, was ‘less than with any single glass,’ while the performance was in other respects satisfactory. ‘Observing the advantages resulting from this combination,’ Lister ‘tried some others,’ among the rest two of Tulley's triple glasses, each of which taken singly was of fine performance. But, instead of unmixed improvement resulting, he noted: ‘N.B. Each glass separately shows a bright object all over the field without bur, and is not far from being achromatic. But combined the objects not in the centre have a strong bur inwards, the colour is much under-corrected, and the spherical aberration is not right.’

In the following year similar anomalous appearances were recorded. Thus, on one occasion, on using in combination a triple glass of Tulley's, free from coma and otherwise excellent, and a double plano-convex in which, when used alone, the spherical aberration was rather under-corrected, and an outward coma presented itself, the combination proved to have the spherical aberration rather over-corrected, and showed an inward coma. Again, a bi-convex glass of Herschel's construction, consisting of a biconvex of plate with a flint meniscus, when used alone with the flint surface foremost had little or no coma, but when combined with a triple 9/10 free from coma showed a ‘bur much inwards.’ The same glass used alone with the plate side foremost showed a ‘bur inwards,’ but when it was combined with the triple, which had before had the effect of inducing an inward coma, the bur inwards was changed to a ‘bur slightly outwards.’

Lister did not despair of finding an explanation of these perplexing and apparently inconsistent results, and in November 1829 a set of five plano-convex glasses manufactured by Utzschneider and Fraunhofer, very similar to those of Chevalier, but uncemented, having been placed freely at his disposal by Robert Brown, the botanist, he earnestly set to work to solve the difficult problem. His experiments he recorded in a series of tables, the first of which gives an accurate description of each of the five new glasses, and also of those of Chevalier, and of their performance when used singly. The others give the effects of various combinations of those glasses upon the chromatic and spherical aberrations and upon coma. He had previously observed in 1827 that in a particular combination of two glasses the coma was diminished by separating the glasses. And in these tables the performance of each combination is given, both when the glasses are close and when they are separated a certain distance from each other. The tables supply abundant evidence of the great effect produced upon coma and upon spherical aberration by the distance between the glasses; but the effects appear altogether inconsistent, and indeed contradictory.

Yet out of this apparent confusion Lister educed a principle which reconciled all the conflicting appearances, and formed the basis upon which all fine combinations for high powers of the microscope have since rested. He found that in a plano-convex lens, constructed like those above described, in which a double convex of plate has its colour corrected for a moderate aperture by a plano-concave of flint, the effect of the flint lens upon the spherical error caused by the plate lens varies remarkably according to the distance of the luminous point from the glass. If the radiant is at a considerable distance, the rays proceeding from it have their spherical error under-corrected; but as the source of light is brought nearer to the glass, the flint lens produces greater proportionate effect, and the under-correction diminishes till at length a point is reached where it disappears entirely, the rays being all brought to one point at the conjugate focus of the lens. This, then, is an aplanatic focus. If the luminous point is brought still nearer to the glass, the influence of the flint lens continues for a while to increase, and the opposite condition, of over-correction, shows itself; but on still greater approximation of the radiant, in consequence apparently of a reversal of the relations to each other of the angles at which the rays of light meet the different curves of the lens, the flint glass comes to operate with less effect, the excess of correction diminishes, and at a point somewhat nearer to the glass vanishes, and a second aplanatic focus appears; and from this point onwards under-correction takes the place of over-correction, and increases till the object touches the surface of the glass. Such a lens, then, has two aplanatic foci; for all points between these foci it is over-corrected, but under-corrected for points either nearer than the shorter, or more distant than the longer focus.

In a paper in the ‘Philosophical Transactions,’ read 21 Jan. 1830, Lister showed how a knowledge of these facts would enable the optician to combine a pair of compound achromatic lenses with perfect security against spherical error. ‘The rays,’ he wrote, ‘have only to be received by the front glass from its shorter aplanatic focus, and transmitted in the direction of the longer correct pencil of the other glass.’ The light then proceeding through each glass, as if from one of its aplanatic foci, is brought correctly to a focus by the combination. Supposing two glasses to have been so arranged, if the front glass is carried nearer to the back one, light proceeding from the shorter aplanatic focus of the front glass will reach the back glass as if from a point nearer than its longer aplanatic focus, that is to say from a point between the foci, and therefore the spherical error will be over-corrected. On the other hand, separation of the glasses beyond their original interval produces under-correction. Thus, by merely varying the distance between two such lenses, the correction of the spherical error may be either increased or diminished at pleasure according to a definite rule, and slight defects in the glasses can be remedied by simply altering their relative position, the achromatism of the combination being meanwhile little affected.

Lister also explained the relation of the aplanatic foci to the coma. At the shorter focus the coma is inwards, at the longer focus it is outwards; and in a combination of two lenses arranged as above described, the inward coma from the shorter focus of the front glass destroys the outward coma from the longer focus of the back glass, and ‘the whole field is rendered beautifully flat and distinct.’

The same principle applies when the lenses are of different form, and when more than two are combined. Thus Lister reduced the manufacture of the achromatic object-glass from a matter of uncertainty and empiricism to a scientific system, and it has become susceptible of a degree of perfection that would otherwise have been impossible.

But Lister continued his labours after he had discovered the principle of construction. A section of his notes is labelled ‘Memoranda on object-glasses made for experiment, December 1829 to May 1830,’ including highly interesting accounts of the effects of glasses made by his own hands. He wrote to Sir John Herschel on 24 Feb. 1831: ‘Finding, however, that W. Tulley was too busy to pursue for me the experiments I wished for ascertaining how compound object-glasses could be combined to the greatest advantage, I determined in November last to make a trial myself. The result was, I acknowledge, beyond my expectations; for without having ever before cut brass or ground more than a single surface of a piece of glass, I managed to make the tools and to manufacture a combination of three double object-glasses, without spoiling a lens or altering a curve, which fulfilled all the conditions I had proposed for a pencil of thirty-six degrees.’ … ‘About three weeks ago I made a second and more complicated trial projected for obtaining the same effect with a much larger pencil. This is just finished, but not without altering one of the original curves, and its plan might be improved if I could spare time to make another set. Still I flatter myself these attempts would interest thee, as showing how easily the principle I mastered may enable an utter novice in glass-working to produce vision which I have not yet seen exceeded.’ In the second of these trials he deviated from the plano-convex form of the lenses, employing a combination of three, of which the front was a double meniscus, the middle a triple, and the back one a double plano-convex. The reasons for preferring these forms are given in full detail in his notes, among which occurs the ingenious idea of regarding the triple with the middle of flint glass as divided by an imaginary line through the flint into two double achromatic glasses, each of which may be considered separately as having two aplanatic foci. The object he proposed to himself was ‘a construction fitted to obtain the largest pencil with good front space and without coma;’ and after describing the mode by which this was arrived at, he says: ‘This combination proves most satisfactorily the advantage of keeping the angles of the rays at all the different curves moderate, the vision being singularly definite and easy. … Indeed, taking all together, I think I have met with nothing to equal it, the distance of the front glass from the object being 0.11 full.’

Having now completely satisfied himself of the applicability of his principle, he devoted much of his leisure for several years to various investigations by aid of the instrument which he had so greatly improved. He thus brought to light many new facts regarding the structure of the animal body. He was the first to ascertain the true form of the red corpuscle of mammalian blood, and selections from his observations on zoophytes and ascidians, beautifully illustrated by sketches from life by the camera lucida, form a classical paper in the ‘Philosophical Transactions,’ 1834. A laborious inquiry, chiefly conducted by means of the microscope, into the limits of human vision, as determined by the nature of light and of the eye, has not been published. He had prepared an account of it for the press, and was on the eve of publication when he learned that the astronomer royal, Professor Airy, had reached the same conclusions, though by a different road, and so abandoned the idea.

In 1837 A. Ross made an unsuccessful experiment with ‘three glasses to admit a large pencil.’ Lister thereupon suggested a combination of three glasses ‘for the same object;’ he gave the dimensions of the lenses and the curves of the various surfaces, with a statement of the effect proposed to be produced by each glass upon spherical aberration and coma. This resulted in Ross's celebrated ⅛ inch object-glass, the construction of which was afterwards adopted by the other principal London makers.

For many years after this date Lister continued to aid the opticians in the construction of the microscope. He died on 24 Oct. 1869, in the eighty-fourth year of his age.

Various improvements have been since introduced both in this country and abroad in the construction of the achromatic object-glass; but Lister's law of the aplanatic foci remains the guiding principle as ‘the pillar and source of all the microscopy of the age.’ Lister rendered services to scientific study that can hardly be overestimated.

Lister married, on 14 July 1818, Isabella, daughter of Anthony Harris of Maryport, Cumberland. She died on 3 Sept. 1864. By her Lister was father of four sons, including the present writer, and of three daughters.

[Lister's manuscript notes and personal knowledge.]

J. L.