At first, British photographer Martin Usborne just wanted to do some reporting on people who leave their dogs locked up in cars. But as he went around scouring parking lots, “making barking noises to try and awaken sleeping dogs that were not actually there,” his project took on a new artistic direction. “The Silence of Dogs in Cars” was inspired by a “childhood memory of waiting in a car whilst his parents were shopping in a supermarket, and the youthful fear that they would not return.”

The Grand Canyon Skywalk is a transparent horseshoe-shaped cantilever bridge and tourist attraction in Arizona near the Colorado River on the edge of a side canyon in the Grand Canyon West area of the main canyon. USGS topographic maps show the elevation at the Skywalk's location as 4,770 ft (1,450 m) and the elevation of the Colorado River in the base of the canyon as 1,160 ft (350 m), and they show that the height of the precisely vertical drop directly under the skywalk is between 500 ft (150 m) and 800 ft (240 m).

A man poses with his water buffalo during “Mekepung” traditional water buffalo race on July 28, 2013 in Jembrana, Bali, Indonesia. Meaning “to chase around”, Mekepung was originally designed as a fun game for peasants to spend their free time when the harvest time was ended, as they were waiting for the start of the planting season. (Photo by Putu Sayoga)

In this photo provided by Skydive Chicago, escape artist Anthony Martin falls while handcuffed and locked inside a box after being dropped from an airplane over Ottawa, Ill., Tuesday, August 6, 2013. (Photo by Joe Silva/AP Photo/Courtesy of Skydive Chicago)

A design studio has launched its own dogs of war – by cleverly blending iconic Second World War planes with their canine counterparts. Photo: Wellington bomber with Golden Retreiver camoflage. A design studio has launched its own dogs of war – by cleverly blending iconic Second World War planes with their canine counterparts. (Photo by BNPS)

An enterprising Chinese man pulls a bicycle cart packed high with bags of recyclable plastic containers in Shanghai July 25, 2002. The man sells each kilogram (2.2 pounds) of plastic for 0.08 yuan ($.01) to a nearby depot. (Photo by Claro Cortes IV/Reuters)

Twenty five life-size donkeys have been given pride of place in St Paul's Cathedral as part of an interfaith exhibition. They've been painted by Egyptian and Western artists, to show solidarity for the people of Egypt. Photo: Artist painted donkey statues are displayed in the “Caravan” exhibition on August 30, 2013 in London, England. (Photo by Peter Macdiarmid)

Lil Bub is a female “perma-kitten” house cat born with several genetic mutations causing dwarfism, polydactylism and disformed lower jaw. Bub rose to fame online after her owner Mike Bridavsky began uploading videos of her to YouTube in November 2011.