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The Effect of Gravity on an Organism
Jun 6 2011 7:52:56 am EST
Topics:Through his studies on swimming, walking, and flight, D’Arcy Wentworth Thompson determined that in every case, speed tends to vary as the square root of the linear dimensions on an animal (Froude’s Law). He also notes that as the length of a limb decreases, its rhythm tends to increase rapidly, due to the simple fact that decreasing the length of a pendulum proportionately increases the rate of swinging.
He extends his observations to all the rhythmic motions of the body, such as heart rate and rate of breathing, noting that as size decreases, the tempo increases. In other words, a mouse’s heart rate and breathing is much faster than ours, while an elephant’s is much slower than ours.
Furthermore, he notes the profound effect gravity has on the form and action of most all organisms, and changing the force of gravity would have a dramatic effect on the growth and form of an organism. Consider the following passage from
On Evolution Of Flight, D'Arcy Wentworth Thompson
Jun 5 2011 9:26:02 am EST
Topics:Nature has developed many dynamic and efficient solutions to break its ties to the ground. The soaring Bald Eagle circles upwards in thermal updrafts, catching the wind in its long broad wings, gliding from updraft to updraft during migration. The Wandering Albatross repeatedly dives into the valleys of ocean waves, wheeling back up into the air, utilizing dynamic soaring to travel many thousands of miles using very little energy from flapping. Canadian Geese maintain continuous flapping flight in formation to reduce drag. The voracious hummingbird beats its wings anywhere from 8-100 times a second, depending on size, and generates thrust in both the upstroke and downstroke to maintain hovering flight. Not to mention the wonders of insect flight…
However, nature, as man, began with rudimentary evolutionary experiments. As we have refined human technology over hundreds of years, so has nature over hundreds of millions of years.
D’Arcy Wentworth Thompson summari
I found this article in the April 30, 2003 edition of Ballston Journal. It was about a theater group I helped form with Kathleen Dunham. I wrote a play entitled “Whodunnit,” to be performed for Ballston Spa’s “19th Century Day.”
The play was a 19th century comedic murder mystery. The plot took place at the San Souci hotel in Ballston Spa. Kathleen Dunham directed the play, and did a wonderful job.
View Hi-Rez image of article:
The play was very well received, the audience was laughing the whole time. It inspired me to continue my writing, and ultimately publish a novel, just as I hoped for.
The interesting part is that just six days off from exactly eight years, The Ballston Journal wrote another front page article in the same spot about the novel I published. It’s like another chapter i
This Northern Goshawk maneuvers through increasingly difficult obstacles, utilizing its large tail to maintain lift while the wings are closed.
On Flight Dynamics: Influence on Living Systems
May 31 2011 1:33:00 pm EST
Topics:Regarding flight, D’Arcy Wentworth Thompson expresses the unique requirements to remain aloft, and the effect these requirements have on the structure of an organism. From On Growth and Form:
The bird’s case is of peculiar interest. In running, walking or swimming, we consider the speed which an animal can attain, and the increase of speed which increasing size permits of. But in flight there is a certain necessary speed—a speed (relative to the air) which the bird must attain in order to maintain itself aloft, and which must increase as its size increases. It is highly probable, as Lanchester remarks, that Lilienthal met his untimely death (in August 1896) not so much from any intrinsic fault in the design or construction of his machine, but simply because his engine fell somewhat short of the power required to give the speed necessary for its stability (41).
…a bird,
Author: Chris Bemis
An 1888 lenticular truss iron bridge, built by the Berlin Iron Bridge Co. that was donated by Washington County to the Town of Malta.
Keeping a Time Capsule
May 30 2011 3:15:38 pm EST
To my good fortune, I had an insightful kindergarten teacher. We made a personal time capsule to open at graduation. Forgetting about it completely, I was very much excited to happen upon it as a young adult.
I wasn’t sure what to do about the contents after I perused them. I decided to put everything away to read again; so it sat for a while.
After some time, I acquired things of interest: letters of gratitude from strangers, brilliant birthday cards, pictures, and other such novelties that I typically lose or throw away over time. Out of guilt, I put these things in the time capsule, lest they be lost forever.
Over time, I accumulated quite a collection of memories, and I had to transfer the contents from an envelope, to a box. I decided not to open the box until I reach a ten year mark in my life. In other words, the next time I’ll open the box is 30, then, 40, 50, and so on.
Every time I add things to the box, I wonder about the things I forgot. I look forward to op
The Mechanics of Walking: Levers And Pendulum Swings
May 30 2011 11:51:43 am EST
Topics:Walking and running has evolved to generate as much thrust as possible while using the least amount of energy. The process of human walking recovers approximately sixty per cent of the energy used due to pendulum dynamics and ground reaction force. However, the legs are not simple straight poles that swing uniformly like the pendulum in a clock; a leg swings and thrusts at the hip, knee, ankle, and toes, utilizing a dizzying array of muscles, ligaments, tendons, bones, and other tissues.
Looking at a human gait cycle, it consist of 60% stance, 40% swing. In other words, the leg spends more time thrusting than it does swinging forward to the next step. Yet one foot has to always be in contact with the ground. In order to maximize thrust while minimizing swing time, the leg is extended while it is in contact with the ground, while the various levers are contract
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On Jumping Height of Organism: Borelli's Law
May 29 2011 12:43:36 pm EST
Topics:Giovanni Alfonso Borelli (1608-1679) was a Renaissance Italian physiologist, physicist, and mathematician. He was a pioneer in the field of biomechanics, publishing De Motu Animalium I and De Motu Animalium II, which explored the mechanical nature of biological systems.
D’Arcy Wentworth Thompson frequently sites Borelli’s work, and explores an interesting phenomenon in which a similarly constructed organism, regardless of size, will jump to the same height. In other words, a flea and a grasshopper, despite their differences in size, end up jumping to the same height. Consider the following passage in On Growth and Form (36-37):
Such problems as that presented by the flea’s jumping powers, though essentially physiological in their nature, have their interest for us here: because a steady, progressive diminution of activity with increasing s
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Heat loss in an organism is proportional to the surface area, or the square of its linear dimensions; the larger the surface area, the greater the heat loss. If the tissues of all homeotherms were to generate heat uniformly, the overall generation of heat would be proportional to the mass of the organism, or the cube of its linear dimensions. In other words, the larger the organism, the more tissue to generate heat, and the more heat generated overall.
However, this is not the case. Smaller mammals must overcome the effects of a larger surface area by generating more heat per unit of mass. Consider the following passage in On Growth and Form:
The tissues of one mammal are much like those of another. We can hardly imagine the muscles of a small mammal to produce more heat (caeteris paribus) than those of a large ; and we begin to wonder whether it be not nervous excitation, rather than quality of muscular
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