A body falls straight or ...?

Guglielmini experiment

It showed that a body dropped from a height not have

a rectilinear motion because the Earth's rotation

Read more in: http://en.wikipedia.org/wiki/Giovanni_Battista_Guglielmini

Foucault pendulum: a straight cable to measure a rotation

The Foucault pendulum (1870) made it possible to demonstrate for the first time directly the phenomenon of Earth's rotation. It is a sphere of lead covered with iron and it suspended from the ceiling by a long steel cable that is put into oscillation to demonstrate the phenomenon of Earth's rotation.

Read more information in:
http://en.wikipedia.org/wiki/Foucault_pendulum
http://www.museoscienza.org/dipartimenti/catalogo_collezioni/scheda_oggetto.asp?idk_in=ST060-00037&arg=Astronomia

Boundaries

From straight to curved

The clip is a small metal object that serves to bind together two parts.

Generally it combines a few sheets of paper in a non-permanent way.

The clip comes from a straight metal wire which is then

curved to get the desired shape.

There is also a machine to produce paperclip. To view this click here

Rhumb line and Great-circle_distance

Great-circle_distance

Rhumb_line

ABC

A_accordion_fisarmonica
B_blade_lama
C_curly_riccio
D_disk_disco
E_ellipse_ellisse
F_fan_ventaglio
G_girder_trave
H_hunchbacked_gobbo
I_infinite_infinito
J_javelin_giavellotto
K_knife_coltello
L_line_linea
M_meridian_meridiano
N_nail_chiodo
O_orthogonal_ortogonale
P_posture_postura
Q_queue_coda
R_road_strada
S_spring_molla
T_tube_tubo
U_U turn_inversione a U
V_voiceprint_impronta vocale
W_wave_onda
X_x-axis_ asse delle x
Y_y- axis_ asse delle y
Z_zig zag_zig zag

Symbolism in some prehistoric curved signs

A basic element in Western ideography, the clockwise spiral (starting from the middle) is strongly associated with water, power, independent movement, and migrations of tribes. The sign's association with water may rather focus recurring rainy seasons, than water in general. In accordance with the law of the polarity of meanings of elementary graphs  also often seems to denote the sun. But maybe not the ordinary sun, but the eclipsed sun.

A more circular and closer version of the previously is seen on many Neolithic rock carvings. The meaning of this ideogram has eluded researchers, but things have now changed. On rock carvings in Scandinavia one often finds signs which look like a strange type of boats or sleighs with short vertical lines on them.

Together with them a lot of small, round signs. A breakthrough to understanding of these strange ideograms seems to have been made in 1991. An archaeologist got the idea that the small, round signs on those rock carvings could be signs for stars in the sky. Thanks to a PC program he found that the rock carvings were documentations of the configurations of the visible planets and the brightest of the fixed stars at times of total solar eclipses. Thus the sign  might mean the eclipsed sun.

An other variation consists in two spirals interconnected , made up not by lines but by rows of dots. This symbol has been found engraved on an amulet of mammoth tooth which is 24,000 years old, and thus must have been engraved by Cro-Magnon mammoth hunters. The sign , often used to denote the sun, is at the center of the amulet, with two on each side of it. During the Bronze Age  it was a structure used for decorations of artefacts of all types. In ancient Greece it was common on vases and amphoras, and often signified water or the sea. A final variation on the same theme is  found on rock engravings from the Bronze Age in Sweden.