Saturday, 26 May 2012

The intimate study of lenses and tidepools

There was invariably pinned to his shirt pocket a twenty-power Bausch & Lomb magnifying glass on a little roller chain.  He used the glass constantly.  It was a very close part of him - one of his techniques of seeing. 


About Ed Ricketts. In Log from the Sea of Cortez. J. Steinbeck. Viking Press, New York. 1951

In 1951 John Steinbeck published The Log from the Sea of Cortez. This book was the narrative portion of a much longer book that had been written and published by Ricketts and Steinbeck in 1941; Sea of Cortez: A Leisurely Journal of Travel and Research. The shorter book did not have the extensive phylogenetic catalogue that Ricketts had written but it did include a eulogy to Ricketts, About Ed Ricketts, written by Steinbeck. This was a highly personal account by Steinbeck about the life and premature death of Ricketts, written with the aim of `laying to rest the ghost' of his close friend. This piece describes the life and works of Ricketts and his approach to science, poetry, art and life. It is in this essay that Steinbeck specifically mentions the way that Ricketts habitually used his magnifier as a way of seeing. But there is other evidence - the photographer Fred Strong took a picture of Ricketts in 1935 that shows him in a dark tweed jacket and softly tailored shirt. On his right lapel at chest height is pinned a small roller chain holder connected to the polished nickel case of his twenty-power Bausch & Lomb.

Ricketts was a highly skilled field naturalist and would have chosen a hand magnifier that met his particular needs as a marine biologist. He chose this distinctive technique of seeing carefully. From other evidence it is clear that when it came to scientific apparatus Ricketts was known to be precise. In fact he was even precise in his selection of non-scientific apparatus -- he equipped his typewriter with umlauts, accents and cedillas so that he could correctly incorporate German, French and Spanish quotations and extracts into his numerous letters. Steinbeck specifically noticed the make of magnifier that Ed Ricketts habitually used -- a Bausch & Lomb. It is not surprising that Ricketts would have chosen a Bausch & Lomb lens, they are a famous American optical manufacturer who had been making high quality optical lenses in Rochester, New York state, since 1853.  


Optics is a surpringly conservative technology, in the sense that once invented a really good optical design has surprising longevity. For example, the 1929 Bausch & Lomb catalogue that Ed Ricketts would have been familiar with, lists three types of twenty-power magnifier; a Hastings Aplanatic Triplet, a Triple Aplanatic and a Coddington. All three of these designs had their origins in the 1800's. The original idea behind the Coddington lens was from 1812, the Steinheil Triple Aplanatic from 1866 and the Hastings triplet was invented in 1879. Furthermore, in spite of the 80 years of optical science innovation that separates 1929 and the present, Bausch & Lomb still manufacture and sell Coddington and Hasting triplet twenty power lenses today.  


All three of the 20X lens designs sold by Bausch & Lomb in 1929 were of good quality and established optical design. They are all constrained by the same fundamental physics of how light interacts with glass, but each represents a different technological approach for obtaining high magnification with minimal spherical aberration. As the name suggests, the triplet designs are made by bonding three separate pieces of glass together to create a single magnifier. Traditionally, and until the late 1940's, the optical cement used for this type of bonding was Canada Balsam, a filtered preparation of the resin of the balsam fir tree Abies balsamea. The refractive index of solidified Canada Balsam is similar to many common optical glasses and it can be used as an optical cement because it dries without crystallising (Mills, A. (1991). Canada Balsam. Annals of Science, 48, 173-185.) The Coddington design lens doesn't use multiple glass elements --  it reduces aberration by cleverly shaping a single piece of optical glass.


The best corrected magnifier available to Ed Ricketts for his marine biology work was the Hasting Aplanatic Triplet, named after its inventor, the American optical physicist Charles Sheldon Hastings (1848--1932). The relative quality of Hastings triplet design versus other available hand magnifiers can be gauged from their retail prices; in 1908 a Coddington retailed for $1.25; a Triple Aplanat was $3.25 and a Hasting Triplet was $6.25.

Charles Sheldon Hastings was born into a professional family at Clinton, New York, in 1848. He was according to one obituary; `...  descended on both sides from a long line of New England ancestry, among whom were an unusual number of professional men: ministers, educators, and especially physicians'.  Hastings' father was a prominent physician who gave lectures on anatomy and physiology in New England schools and hospitals. He had a good relationship with his son Charles, in particular supporting his son's scientific interests.

Charles Hastings studied at Hartford High school, Connecticut and then enrolled to study physics at the Sheffield Scientific school of Yale University. He graduated from Yale with a bachelors degree in physics in 1870 and then received a doctorate in 1873. After a period working at Yale as a demonstrator Hastings then spent three years on a scientific  grand tour of European universities; attending courses on physics and advanced mathematics with Helmholtz in Berlin, Kirchoff and Konigsberger in Heidelberg and Steinheil in Munich. Hastings then travelled from Germany to Paris, where he studied at the Sorbonne during 1875, funded by a Tyndall Scholarship.

There were very few American science students of the 1870's who enjoyed the advantages that Hastings had. Studying with such brilliant physicists as Helmholtz and Kirchoff made a big impact on his learning and his approach to physics. Helmholtz in particular had a deep appreciation of the connection between the physiological optics of the eye and man-made optical instruments.

When Hastings returned to the USA  in 1876, it was to a newly created post in a new University. At the age of 27 he joined the Johns Hopkins University in Baltimore as one of seven `associates' who joined six newly appointed professors. This was a vibrant team; not one of the associates was thirty when they were appointed. Eight years later Hasting returned to Yale to become director of the physics lab in the Sheffield Scientific School, a post he held until 1915.

Hastings spent much of his professional life on the difficult problem of designing optics and lenses for lab usage and for use in the larger and larger telescopes that astronomers were demanding for their observational work. The standard formulas used at the time for calculating how a given lens system would work in practice were extremely complicated. In addition, for many practically useful lens systems, they were almost impossible to use to the accuracy required for a lens grinding workshop. Hastings developed his own methods to make these calculations, using only four figure logarithm tables instead of offices full of `computers'; meaning at that time human beings calculating longhand. Hasting also developed his own spectrometer for making very accurate measurements of the refractive index of optical glasses. This instrument was used by him over a forty year period and with a combination of his mathematical methods and experimental data, he developed an unrivalled knowledge of how to design lenses.

Although Hastings was an outstanding academic physicist and a brilliant lecturer and teacher he was not divorced from the real world. After having trouble finding skilled lens grinders he educated himself in the practical skills needed to grind lenses of particular curvatures, visiting lens makers in the USA, England, Germany and France to really learn this trade. Even more significantly, from the late 1880's onwards, Hasting developed a very fruitful collaboration with an optical instrument company in Pittsburg run by John A. Brashear and his son-in-law James B. McDowell. Although both Brashear and McDowell were gifted opticians, they had realised that the very large and high quality optics need in astronomy and astrophysics required a much more profound theoretical understanding than either of them had. Hastings rapidly became a vital part of the Brashear company;     

On the one hand, it gave Brashear and McDowell the technical advice without which they could hardly have developed as they did; and on the other, it gave Hastings precisely the clinic he needed to put to use his unrivalled skill and knowledge in matters optical.

Hastings, Brashear and McDowell were a remarkably succesful team. Many of the largest and highest quality astronomical telescopes made in the USA  during the early years of the 20th century were created by them. Telescopes made using the formulas and knowledge of Hastings had lenses that ranged from 16-inches in diameter, up to a 30-inch photograpic objective at the Alleheny Observatory. A number of these lenses and telescopes are still in use today.

The  technical basis for the Hastings Triplet was created by Charles Hastings in the late 1870's, and in 1879 he summarised his experimental work and insights in a set of formulae that could be used to design a triplet lens that was intrinsically colour corrected (C.S Hastings (1879). Triple Objectives with complete Color Correction, The American Journal of Science and Arts, 3rd series, vol. 18, pp. 429-435).  By the late 1890's these formulae had been used by a number of optical instrument manufacturers in the USA. By 1897 the Hastings Triplet was being described in Edward Bausch's handbook on microscopy and the Bausch & Lomb catalogue for 1901 lists Hastings Aplanatic Triplets for sale, with an explicit reference to the formulae of Prof. Chas. S. Hastings of Yale University . They describe them as follows;

These lenses offer advantages found in no other hand magnifiers, the improved construction being possible through the recent improvements in optical glass. The field embraces a very wide angle, and the working distance is almost equal to that of a simple lens of the same power. The defining power is such as to show structures not visible with other magnifiers of equal power.

To this day, Bausch & Lomb still make and sell Hastings Triplet hand magnifiers. They remain as they were described in 1901, offering  advantages found in no other hand magnifiers . There are very few technologies that were invented in the 1880's and are still in routine use today, virtually unchanged and unimproved 130 years later. They are a testament to the outstanding lens making skills of Charles Sheldon Hastings.      

It is interesting to reflect on the role that a single, seemingly modest,  instrument, the Hastings Triplet magnifier, allowed Ed Ricketts' to use intense seeing in his ambitious program of discovery in marine biology. The brilliance of Charles Sheldon Hastings was bequeathed to Ed Ricketts, via the agency of the Bausch & Lomb Optical Company, as a means to obtain more discrimination from his already incredible observational ability. No matter how passionately Ricketts wanted to see the tiny creatures of the tide pool, and this passion was evident and seemingly inexhaustible, without the Hasting triplet his eyes simply couldn't have seen the detail. Ricketts needed a particular artefact, created from the work and insights of Hastings, to increase the power of his eyesight. Within this delicate dance of sublime optical physics and a drive for ecological insight on the Pacific littoral, we can see many of the general issues that arise when we set ourselves the task of intense seeing.

The Hastings Triplet lens illustrates the fact that human faculties can be readily extended by technological means, and thereby allow us to increase our intensity of seeing. For Ed Ricketts this technological extension was the outwardly humble twenty-power Bausch & Lomb magnifying glass . Without exception these technological means  must  have limitations that are dictated by the fundamental laws of physics;  laws that operate everywhere and at all times . For glass lenses in air, the laws governing refraction and the wave nature of light dictate the focal volume of a lens.  These physical laws set the limits on the volume of the world that can, at any one time, be enlarged and thus subjected to a higher intensity of scrutiny than that of the unaided human eye. But in addition to the  fundamental  physical limits on these lens technologies, there are also much more prosaic constraints. For example, the Hastings lens design relies on finding a suitable optical cement and the Coddington does not. Luckily, the optical cement used in the construction of the Hastings triplet is sufficiently waterproof that Ricketts could use it in his beloved tidepools. If it hadn't have been waterproof, he would have had to rely on the Coddington lens which is ground from a single block of glass and is therefore inherently waterproof. You cannot see detail as clearly through a Coddington lens as you can through a Hastings triplet. 

Great  insights are often built on the foundation of a visceral need to see. They are realised by years of deliberate practice and a repeated striving for insight. For Ed Ricketts this need to see drove him again and again to get out and observe the marine ecology he saw everywhere in his adopted homestead on the Monterey peninsula. He was driven by the need for `breaking through' in his understanding of the Pacific littoral. Ricketts role in marine biology and species discovery is reflected in the fact that about twenty marine organisms have species names of  rickettsi  or  steinbecki , in honor of Ricketts and Steinbeck. For example, these include  Eubranchus steinbecki , a nudibranch named in 1987;  Catriona rickettsi  a nudibranch named in 1984;  Pycnogonum rickettsi  a sea spider named in 1934 and  Polydora rickettsi  a spionid polychaete named in 1961. 


All observations made at high magnification are in some sense artificial, they need to be conciously linked back to the macroscopic world. It is fascinating to find out that the insights dervived by Ed Ricketts from his high magnification observations of tiny invertebrates in the tidepools of California had a significant impact on John Steinbeck. Although  Cannery Row  is seen as one of John Steinbeck's more lightweight books, for example compared with the social themes in  Grapes of Wrath , in fact it is a book composed at multiple levels and was conciously built by Steinbeck on the ecological principles that he learnt from his own and Ed Ricketts' observations of microscopic life in the tide-pools. Ed Ricketts showed that  intense seeing  pays dividends. He built a lasting legacy of marine biology exploration and ecological thinking on the back of his dedicated and energetic engagement with the world; macroscopic and microscopic.

References:

Charles Sheldon Hastings is almost completely invisible as a scientist. There are, to my knowledge, no biographies of him and his archives at Yale University appear to be sitting quietly in the corner of an archive room without being actively bothered by anyone. The information in this post about Hastings has been derived from the following obituaries and memoirs.

Beach, F.E. (1932). Charles Shedldon Hastings. Science. New Series Vol 75, No 1947, pp 428-430.

Schlesinger, F. (1932). Charles Sheldon Hastings. The Astrophysics Journal. Vol 76, No(3), pp 149-155.

Uhler, H.S. (1938). Biographical memoir of Charles Sheldon Hastings 1848-1932. Biographical Memoirs of the National Academy of Sciences. Vol 20. pp273-291.




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