Fournier 1996

Fournier, Marian. The Fabric of Life: Microscopy in the Seventeenth Century. Baltimore: The Johns Hopkins University Press, 1996.

early 1660s, Hooke anticipated the microscope would discover nature's hidden secrets; by 1690s, microscopy had been abandoned by all but Leeuwenhock and a few amateurs, who continued investigating well into the c18 but whose "discoveries" did not contribute significantly to scientific innovation (6-7)

• principle investigators during this period: Hooke, Malpighi, swammerdam, Grew, and Leeuwenhoek

pre-1660, only one basic design for microscope used, which had been around ~50 years; post-1660, many different designs found in contemporary publications -- i.e., increased interest in microscope around 1660, although it had been around for almost half a century (4)

1. A New Instrument Appraised

1609-1610: Galileo creates an optical device for magnifying small things or distant objects; early version of the telescope

• not the first -- generally invented by spectacles manufacturers ca. 1600
• but Galileo did introduce telescope to scientific practice (10)
• Sidereus nuncius, 1610; discuses observations of the moon using his "perspicillum"

Kepler, Dioptrice, 1611; introduced changes to Dutch telescope known as "Keplerian arrangemetn", which almost replaced Dutch telescope by 1640

1620s, Cornelius Drebbel began making/distributing microscopes of Keplerian arrangmeent

early problems: inadequate/poor-quality glass; spherical aberrations because of refraction through curved lenses; chromatic aberration

field lens, a third lens that increased field of vision, introduced around 1650; Hooke used it for some work, then took it out for more detailed examinations (12)

adding more lenses could increase magnification, but tended to increase distortions

1660s, others began using only one very powerful lens to reduce distortions (13)

no microscope dated "unquestionably" from before 1670 survives (14)

most magnified around 50x, but up to 100x; with a resolution of at most ca. 3 microns; simple microscope superior to compound; between 1670 and 1750, little improvement in performance of both simple and compound microscopes (14)

Leeuwenhoek produced a small number of microscopes of superior quality, but most of the ~350 he made during his lifetime were standard for the time (16-7)

improvement in pivot, staging and lighting were introduced ~1660-1750 (18-9)

various designs/improvements (20-24)

Early (pre-1660) Use of the Microscope

insects were the first objects of microscopic study

• Galileo observed one in 1610
• Peiresc and his companion observed insects ~1622
• oldest extant illustration (1625) is of a bee, produced as two broadsheets: one entitled Apiarium, signed by Prince Cesi (studied in collaboration with Francesco Stelluti, Francesco Fontana), as a natural history of the bee; the second engraved illustrating the magnified external parts of the bee, headed Melissographia and signed by Stelluti (For images, see BibliOdyssey post: [[1]]; also, Digital Edition of the Apiarium/Melissographia: [[2]]
  • 1630, Stelluti re-used the illustration in his edition of Persius's poems, accompanied by more detailed description (book available online through ECHO: [[3]])
• "The investigations of Galileo, Peiresc, and Stelluti were all concerned with the outer appearance of the insect body and a few other objects. In fact, the majority of references to microscopic observations in the period prior to 1660 are concerned with the external details of the bodies of insects, and these organisms were to remain favorite objects for a long time to come." (26)

Gioanbatista Odierna, L'occhio della mosca, 1644

• studied the eye of the fly both from the outside and, post-dissection, the inside
• concluded the insect eye is composed of 1000s of identical units, each being an eye
• believed the insect eye both perceives and receives visual perception -- doesn't happen in the brain (27)
• combined microscopic investigation with anatomical procedures -- described how to cut apart fly to better see its structure

Pierre Borel, De vero tellescopii inventore (1655), Observationum microscopicarum centuria

• like most early microscopists, his investigations convinced him of divine order (28)
• thought microscope could be used to study medicine and disease, even speculating that signs of death might be detected microscopically

Establishment of Microscopic Data

"Whereas prior to 1660 microscopic observations frequently appear to have been undertaken in order that scholars might marvel at the wondrous sight of hugely magnified crawling vermin, the natur of such investigations changed during the 1660s to the purposeful study of organic structure." (30)

preparation of the specimen:

• Hooke couldn't observe porousness of cork until he cut a very thin slice
• Grew also developed methodical way of slicing sections of plant material from different angles
• anatomia subtilis, refined anatomical research, required other techniques like boiling, maceration, and injection (32)
• Malpighi injected ink into a kidney, so that glomeruli showed up as black globules (32);
• sometimes these alterations lead to false assumptions about how the tissue worked by changing the specimen (happened for Malpighi with brain)
• desiccation altered the fabric of the body; could remedy by adding water or oil to it while investigating, then keeping dried specimen around for further investigation (as Leeuwenhoek did)

measurements were difficult; could be made by placing a rule next to the microscope, simultaneously looking at it and the specimen (Hooke, Leeuwenhoek), or a natural standard, such as sand or a strand of hair (34-5) -- micrometers not available until mid-18c

critics:

• Theodoor Kerckring; warned Malpighi that the range of vision is small, colors are distorted; "difficult to distinguish what is original and real" (Kerckring quoted on 36)
• Cherubin d'Orleans; warned that investigators must stitch together small images to make a whole; compared looking at large image then small magnified sections to reading, seeing letters pop out