Does the green dot above flash before, as, or after the red dot reaches it? Most people say after, but in fact the flash occurs before the red dot arrives (below). This anomaly is known as the flash-lag effect, and its cause is unclear. Possibly it’s a sign that the visual system extrapolates the position of a moving object more readily than that of an unpredictably flashing one.
When a thread is pulled horizontally from the underside of a wound spool, the spool rolls in the direction of the pulling force, counter to intuition. When the thread is pulled upward vertically, the spool rolls in the opposite direction.
Why the difference? The spool must rotate about its point of contact with the table, but the direction of torque, clockwise or counterclockwise, varies with the angle of the thread. Interestingly there’s a critical angle at which the spool does not roll but slides.
In 1885, seeking a way to depict vocal sounds visually, Welsh singer Megan Watts Hughes invented the eidophone, a chamber capped with an elastic membrane that would resonate when the singer sang into a tube. When she spread the disk with a thin layer of sand or glycerine, standing waves would register as visible patterns resembling forget-me-nots, daisies, marigolds, chrysanthemums, and sunflowers.
“Stepping out of doors,” she wrote, “[I] have seen their parallels living in the flowers, ferns, and trees around me; and … the hope has come to me that these humble experiments may afford some suggestions in regard to nature’s production of her own beautiful forms.”
The field of study she helped to pioneer is now known as cymatics — see Chladni Figures.
(Thanks, Steve.)
In a 1963 issue of Bokmakierie, a magazine for birdwatchers, Frank A. Goodliffe described a curiously familiar species he called Clericus polydenominata, the “dog-collared sombre blackbird”:
Identification: Similar to common laity but plumage and behaviour should serve to differentiate. Plumage black with narrow white collar — unbroken at throat. Feet black, of leathery appearance. Beak pink — often with blueish tint during winter months. When in groups are often seen with wings folded behind rump. … Habits: Usually found congregating with flocks of common laity, the females of which are frequently seen with plumage of vivid colours. Nesting: This usually occurs close to old buildings with spires. They are usually very friendly and may be seen around nesting sites of common laity at tea-time. … Call: The voice is distinctive, commencing ‘Brrrrr–rethren’ and continuing low and pleasant — often prolonged. Usually sings in congregations.
In a private booklet published four years later, M.A. Traylor suggested that the species belonged in the family of bishop birds.
From Lee Sallows:
(Thanks, Lee!)
Putting mercury in contact with an aluminum plate has some surprising consequences (2:05).
In 1895 a London shopkeeper attracted customers with a glass cask of whiskey — they were puzzled to find that no matter how much liquid they drew off, the level in the cask never dropped. The container could be viewed from any angle, and it stood well away from the wall. How was this possible?
A hidden pipe connected the bottom of the cask to a tank in another room. When a customer drew a glass of whisky, a confederate there would open a tap to replenish tank B, and the liquid, seeking its own level, would maintain the same height in the cask.
(James Scott, “Shopkeepers’ Advertising Novelties,” Strand, November 1895. See Desert Downpour.)
From reader Hans Havermann: Each of these equations uses each of the digits 0-9 exactly once:
8596 = 2×14×307
8790 = 2×3×1465
9360 = 2×4×15×78
9380 = 2×5×14×67
9870 = 2×3×1645
10752 = 3×4×896
12780 = 4×5×639
14760 = 5×9×328
14820 = 5×39×76
15628 = 4×3907
15678 = 39×402
16038 = 27×594 (= 54×297)
16704 = 9×32×58
17082 = 3×5694
17820 = 36×495 (= 45×396)
17920 = 8×35×64
18720 = 4×5×936
19084 = 52×367
19240 = 8×37×65
20457 = 3×6819
20574 = 6×9×381
20754 = 3×6918
21658 = 7×3094
24056 = 8×31×97
24507 = 3×8169
25803 = 9×47×61
26180 = 4×7×935
26910 = 78×345
27504 = 3×9168
28156 = 4×7039
28651 = 7×4093
30296 = 7×8×541
30576 = 8×42×91
30752 = 4×8×961
31920 = 5×76×84
32760 = 8×45×91
32890 = 46×715
34902 = 6×5817
36508 = 4×9127
47320 = 8×65×91
58401 = 63×927
65128 = 7×9304
65821 = 7×9403
(Thanks, Hans.)
