If we were to burn NH4Cr2O7 with HgSCN in the Dark Ages in Europe and show it to anyone, it is us who would be burning next on a fiery cross of Inquisition. And it’s no wonder, since this experiment produces a truly marvelous result. At first, as you ignite the mixture of NH4Cr2O7 and HgSCN, all you can see is that it is slowly burning with a reddish flame. After a while, however, a crater is formed in the middle of the burning pile, and then, suddenly, tentacle-like appendages start sprouting from the burning mixture. And you can almost hear the scream of the mad occultist – “Come forth, Kraken! Come forth!” But of course, this is simply a chemical reaction that is called the "Pharoah's Serpent". It was also often sold in firework stores until people realized that it was toxic.

“The V-30 Warhawk was designed by Blackshaw Avionics as a long-range fighter and was primarily used by the Arcadian Air Force for escort duties. The plane pictured is the “Spirit of Freedom” and was one of the four planes that escorted the Arcadian Royal Airship during and after the Great War. The three other fighters were the “Spirit of Hope”, the “Spirit of Justice” and the “Spirit of Destiny”. All pilots were hand-picked by the Head of Airborne Forces and included some of the very finest pilots in the Kingdom. The crew consisted of one pilot and one gunner although both cabins were fitted so that if either crew member was killed the other could take over their duties. Each Warhawk was fitted with four Haverlock “Banshee” engines and four 24mm machine guns”. (Photo and comment by Jon Hall)

A demonstrator waves Turkey's national flag as he sits on a monument during a protest against Turkey's Prime Minister Tayyip Erdogan and his ruling AK Party in central Ankara June 2, 2013. Erdogan accused Turkey's main secular opposition party on Sunday of stirring a wave of anti-government protests, as tens of thousands regrouped in Istanbul and Ankara after a lull and trouble flared again in the capital. Police used tear gas on protesters in Ankara but the clashes were relatively minor compared with major violence in Turkey's biggest cities on the previous two days. (Photo by Umit Bektas/Reuters)

While communism, collectivism, worms, dry rot and casual looting failed to destroy the majestic wooden churches of Russia, it may be ordinary neglect that finally does them in. Dwindled now to several hundred remaining examples, these glories of vernacular architecture lie scattered amid the vastness of the world’s largest country. Just over a decade ago, Richard Davies, a British architectural photographer, struck out on a mission to record the fragile and poetic structures. Austerely beautiful and haunting, “Wooden Churches: Traveling in the Russian North” (White Sea Publishing; $132) is the result. Covering thousands of miles, Mr. Davies described how he and the writer Matilda Moreton tracked down the survivors from among the thousands of onion-domed structures built after Prince Vladimir converted to Christianity in 988.

Broadway Tower is a folly located on Broadway Hill, near the village of Broadway, in the English county of Worcestershire, at the second highest point of the Cotswolds after Cleeve Hill. Broadway Tower's base is 1,024 feet (312 metres) above sea level. The tower itself stands 55 feet (17 metres) high. The “Saxon” tower was designed by James Wyatt in 1794 in the form of a castle, and built for Lady Coventry in 1799. The tower was built on a “beacon” hill, where beacons were lit on special occasions. Lady Coventry wondered if a beacon on this hill could be seen from her house in Worcester – approximately 22 miles (35 km) away – and sponsored the construction of the folly to find out. The beacon could be seen clearly.

With a presence in nearly every city and town across Iran, the paramilitary Basij volunteer corps has an ever-increasing influence on life in the Islamic Republic. Authorities created the Basij, which means mobilization in Persian, just after the country's 1979 Islamic Republic. It is part of Iran's powerful Revolutionary Guard. Photo: In this Thursday, August 22, 2013 photo, a female member of the Basij paramilitary militia aims a rifle as a trainer looks over her shoulder in Tehran, Iran. (Photo by Ebrahim Noroozi/AP Photo)

An Armatix employee holds a “smart gun” by the company at the Armatix headquarters in Munich May 14, 2014. The gun is implanted with an electronic chip that allows it to be fired only if the shooter is wearing a watch that communicates with it through a radio signal. If the gun is moved more than 10 inches (25 cm) from the watch, it will not fire. A Maryland gun shop owner has dropped his plan to be the first in the United States to sell the so-called “smart gun” after a backlash that included death threats. (Photo by Michael Dalder/Reuters)