An evolving tool at the center of science. A brief history
From Animaculum to single-molecules: 300 years of the light microscope
Adam J. M. Wollman, Richard Nudd, Erik G. Hedlund, Mark C. Leake
Biological Physical Sciences Institute (BPSI), Departments of Physics and Biology, University of York, York YO10 5DD, UK.
Although not laying claim to being the inventor of the light microscope, Antonj van Leeuwenhoek, (1632 –1723) was arguably the first person to bring this new technological wonder of the age properly to the attention of natural scientists interested in the study of living things (people we might now term ‘biologists’). He was a Dutch draper with no formal scientific training. From using magnifying glasses to observe threads in cloth, he went on to develop over 500 simple single lens microscopes1 with which he used to observe many different biological samples. He communicated his finding to the Royal Society in a series of letters2 including the one republished in this edition of Open Biology. Our review here begins with the work of van Leeuwenhoek before summarising the key developments over the last ca. 300 years which has seen the light microscope evolve from a simple single lens device of van Leeuwenhoek’s day into an instrument capable of observing the dynamics of single biological molecules inside living cells, and to tracking every cell nucleus in the development of whole embryos and plants.
Investigation of a claim of a late-surviving pterosaur and exposure of a taxidemic hoax: the case of Cornelius Meyer’s dragon
Phil Senter and Pondanesa D. Wilkins
Here we investigate a claim that pterosaurs survived into the seventeenth century in Italy. In 1696 Dutch civil engineer Cornelius Meyer published an engraving of the skeleton of an alleged dragon from near Rome. Some recent young-Earth creationist authors have used the engraving as evidence against the separation of humans and pterosaurs by millions of years, claiming that the skeleton is that of a pterosaur that was alive in the seventeenth century. The engraving is detailed enough to identify the skeleton as a composite of bones from various extant animal species. Until now, however, no one has attempted such identification. Here we identify the specific animals that were used in the construction of this taxidermic hoax. The skull of Meyer’s dragon is that of a domestic dog. The mandible is that of a second, smaller domestic dog. The “hindlimb” is the forelimb of a bear. The ribs are from a large fish. Ostensible skin hides the junctions between the parts of different animals. The tail is a sculpted fake. The wings are fake and lack diagnostic traits of bat wings and pterosaur wings. No part of the skeleton resembles its counterpart in pterosaurs. This piece of young-Earth creationist “evidence” therefore now joins the ranks of other discredited “evidence” for human-pterosaur coexistence and against the existence of the passage of millions of years. Also, a three-century-old hoax is finally unveiled, the mystery of its construction is solved, and an interesting and bizarre episode in Renaissance Italian history is elucidated.
It consists of a couple of dry pile batteries with a metal ball on a pendulum wire. Two metal bells are at the ends of the ball’s swing. The charged ball swings to a bell, transferring change and then is attracted to the other as the balance of charge has changed. The power drain is small and the amount of energy stored in the battery comparatively large. It also turns out the chemistry, which is not well known, is very robust. It started ringing in 1840 and continues to this day 175 years later.
Some details — batteries are stacks of about 2,000 Zn foil and MnO2 impregnated paper disc pairs. Each cell generates about a volt, so each battery is about 2,000 volts. There is a coating to keep the moisture content stable - as the electrolyte is just water. The current is very low - about a nanoamp so the power is a couple of microwatts. If you work through the arithmetic about 11,000 joules of energy have been delivered over the years. By comparison the battery in an iPhone 5s stores a bit under 18,000 joules. Estimates of the likely energy storage of the dry pile and its leakage are such that the bell should ring for at least a few more centuries.
Maxwell was a master at spotting analogies in different branches of the natural world, and he began by using the steady flow of an imaginary incompressible fluid as an analogy for both electric and magnetic lines of force. This way, he showed that all the known formulae for electric and magnetic forces in static conditions could be derived equally well from the conventional action-at-a-distance theories or from Faraday’s lines of force. A stupendous achievement but, for the present, Maxwell couldn’t think how to deal with changing lines of force. As was his way, he got on with other work while ideas brewed at the back of his mind.
Six years later he came up with a new model. He filled all space with imaginary tiny spherical cells that could rotate and were interspaced with even smaller particles that acted like ball-bearings. By giving the cells a small but finite mass and a degree of elasticity, Maxwell constructed a mechanical analogy for magnetic and electric lines of force, and showed that any change in one induced a change in the other. This extraordinary model yielded not only all the known formulae of electricity and magnetism, it predicted electromagnetic waves that travelled at a speed determined solely by the basic properties of electricity and magnetism, This speed turned out to be within 1½ percent of that at which light had been measured by experiment – compelling evidence that light itself was electromagnetic. An astounding result, but the response of fellow-scientists was muted. The goal in any branch of physics, they believed, was to identify nature’s true mechanism, and they regarded Maxwell’s model as an ingenious but flawed attempt to do this for electromagnetism and light. Everyone expected that Maxwell’s next step would be to refine the model but, instead, he put the model on one side and set out to build the whole theory from scratch, using only the laws of dynamics.
For regions like the US with a mm/dd/yy calendar order today gives 3/14/15 -- the first five digits of Pi 3.1415. going a bit further you get the first ten digits - 3.141592653 - at 9:26:53.
Only one day every century has this relation. And that brings up a curious relation with Einstein whose birthday is today. In 1915 he published his paper on General Relativity. To call it remarkable is understatement of the grandest order.
There is a foundational paper published a bit earlier with an astonishing opening paragraph. A non-technical phrasing might be: “Here is my theory of the dynamics of space and time, with an introduction to its mathematical underpinnings, as well as derivations of all the previous laws of physics within this new framework.” He mentions Grossman, but that was help with the math rather than the underlying physics. I doubt we’ll ever see such a dramatic leap penned by an individual for a theory that holds up to experiment. And it has held solidly for a century!
What you need to do is celebrate. He had a sweet tooth and liked vanilla ice cream cones with chocolate sprinkles. He also had a fondness for fruit, particularly cherry, pie - so perhaps a slice of cherry pie with a scoop of ice cream is appropriate. You might throw care to the wind and add some chocolate shavings or sprinkles...
And it is a day to celebrate William Jones - the person who believed (but didn't prove) the ratio of the circumference to the diameter of a circle was irrational and should have it's own symbol.
the symbol for this ratio known today as π (pi) dates from the early 18th century. Before this the ratio had been awkwardly referred to in medieval Latin as: quantitas in quam cum multiflicetur diameter, proveniet circumferencia (the quantity which, when the diameter is multiplied by it, yields the circumference).
It is widely believed that the great Swiss-born mathematician Leonhard Euler (1707-83) introduced the symbol π into common use. In fact it was first used in print in its modern sense in 1706 a year before Euler's birth by a self-taught mathematics teacher William Jones (1675-1749) in his second book Synopsis Palmariorum Matheseos, or A New Introduction to the Mathematics based on his teaching notes.
Before the appearance of the symbol π, approximations such as 22/7 and 355/113 had also been used to express the ratio, which may have given the impression that it was a rational number. Though he did not prove it, Jones believed that π was an irrational number: an infinite, non-repeating sequence of digits that could never totally be expressed in numerical form. In Synopsis he wrote: '... the exact proportion between the diameter and the circumference can never be expressed in numbers...'. Consequently, a symbol was required to represent an ideal that can be approached but never reached. For this Jones recognised that only a pure platonic symbol would suffice.
I have not come across any indication of Jones' dessert preferences. Then again he was Welsh. Pie in the day was likely meat filled.