 frame|right|allais's paraconical pendulum  the allais effect refers to the anomalous behavior of pendulums or gravimeters, which is sometimes observed during a solar eclipse. the effect was first reported as an anomalous precession of the plane of oscillation of a pendulum for the solar eclipse of june 30, 1954 by maurice allais, a french polymath who went on to win the nobel prize in economics. he reported another observation of the effect during the solar eclipse of october 2, 1959. ==experimental observations== various experiments have been performed in order to detect anomalous behavior during solar eclipses. some observations gave positive results and some failed to detect any noticeable effect. the table below gives an overview of the different experiments. {| class="wikitable sortable" border="1" |- ! experimenter !! date !! place !! device !! result |- | || || || || |- | m. allais || june 30, 1954 || saint-germain-en-laye, france || paraconical pendulum || "the plane of oscillation of the paraconical pendulum approximately shifted 15 centesimal degr. during the eclipse." maurice allais, should the laws of gravitation be reconsidered?, aero/space engineering 9, 46â55 (1959) |- | m. allais || october 2, 1959 || saint-germain-en-laye, france || paraconical pendulum || "an analogous perturbation of amplitude approximately 10 grads has been observed" maurice allais, "maurice allais, l'anisotropie de l'espace ("the anisotropy of space"), clement-juglar, 1997 |- | g. t. jeverdan et al. || february 15, 1961 || iasi, romania || foucault pendulum || the oscillation period of the pendulum decreased by about 1 part in 2000 â the so-called âjeverdan effectâ,g. t. jeverdan, g. i. rusu and v. i. antonescu, "date preliminare asupra comportarii unui pendul foucault in timpul eclipsei de soare de la 15 februarie 1961", analele stiintifice ale universitatii "al. i. cuza" of iasi, section i, tom vii, anul 1961, fasc.2, p. 457 but his report was not published in a mainstream english-language scientific journal. |- | l. slichter et al. || february 15, 1961 || florence, italy || gravimeter || "gravity observations during the solar eclipse of february 15, 1961, failed to detect an associated gravitational signal" slichter l. b., caputo
Fringe_physics Solar_eclipses