The Jaivana cannon, the world's ''largest cannon on wheels'' ever built in modern era - Jaigarh Fort, Rajasthan

Jaivana cannon, world's largest canon,RajasthanFlickr
Jaivana cannon, world's largest canon,RajasthanTripAdvisor
The Jaivana cannon, at the time of its manufacture in 1720, was the world's largest cannon on wheels  ever built in the early Modern Era.  Located at the  well-known Jaigarh Fort, Jaipur, Rajasthan, it was cast in 1720, during the reign of Maharajah Sawai Jai Singh II (1699–1743) of Jaipur.  Jaivana, is, no doubt, the biggest attraction of this fort. Without wheels the Bara Gazi Toph (cannon) built by the Bahmini ruler at Kalabaragai (Gulburga) Fort is believed to the longest one in the world and its presence in the historic fort was discovered a few years ago. In terms of length without wheels, the Nizamabad cannon is the third longest one measuring 23 feet.

Since Jaipur is not that far from Delhi (just 150 miles) and also from NW provinces, considering its strategic location it was vulnerable to attack by enemy rulers all around. Being smart and  intelligent, besides being a visionary Sawai Jai Singh II had a cordial relationship with the Mogul rulers. However, to defend his kingdom and his people, for safety considerations, he focused his attention on the  further development of  the cannon foundry here.  This foundry had been there  in Jaigarh fort since the time of Mogul ruler Shah Jahan and it is believed to have been one of the world's most efficient and prolific cannon foundries. It became a major cannon foundry for the following reasons:  a. Mainly, because of the abundance of quality iron ore mines  near the fort. b. The presence of  a massive wind tunnel in the  cannon foundry of  Jaigarh Fort had an added advantage.  The wind tunnel that sucked air from the high mountains into its furnace causing temperatures to go up as high as 2400 °F, and making the metal melt easily. The molten metal thus formed would fill a reservoir chamber and  then pass into a cannon mold in the casting pit. Most of those cannons made here were massive, mostly 16 ft long and had to be prepared within a single day. c. The Rajput rulers also  had  a large ingenious mechanical device  built that had a well-built precision gear system driven by four/six pairs of oxen; the device was used for hollowing out the cannon barrels.
Jaigarh Fort. /
During the reign of  the Mogul Emperor Muhammad Shah, Jai Singh II became  the official Mogul Qiladar of Jaigarh Fort according to a Firman. Subsequently, Jai Singh II is said  to have molded the great Jaivana Cannon by incorporating special alloy using devices and facilities available in this old and historical foundry inside the Jaigarh Fort. Being  a great warrior as he was, Sawai Jai Singh II  had  maintained a large number of artillery and copious supply of munitions in case of war. Surprisingly, this largest cannon in the world had not been fired even once for the purpose of war. The reason being the Sawai Jai Singh dynasty had a close relationship with the Moguls.
Jaigarh Fort/
Jaivana rests on a high 4 wheeled carriage; the front wheels are 2.74 m in diameter and the rear wheels are 1.37 m in diameter; it weighs 50 tons. Only a well-planned and ingenious preparation would have made it possible a cannon of this massive size whose total length is 20.19 ft and the barrel can be raised or lowered by an 8 ft tall elevating screw. Four elephants were used to rotate the gear system made of   thick wooden crossbars fixed to a central beam. It is these wooden parts that have eroded due to ageing  and need  to be repaired. To ease the burden on the wheels of Jaivana  due to overlying heavy cannon, a new support system is to be made to bear the weight.  The barrel has decorations carved on it  depicting trees, an elephant scroll and a pair of birds (ducks). It is, as mentioned earlier,  mounted on 4 wheels  with two back wheels mounted on roller pin bearings, to turn it 360° and fire in any direction. A tin shed was built to protect the cannon against  vagaries of weather. The cannon had a maximum range of 22 miles 
Jaigarh, Rajasthan, location map. Tutorialspoint
and used 50 kilogram (110 lb) balls.  It causes immense shock waves capable of shaking the nearby buildings. The Gunner had to safeguard himself upon firing  as considerable risk was involved.
The Jaivana cannon  /
The cannon is believed to have been fired only once apparently to test its capability  - towards Chakshu, 22 km away. About 100 kgs of explosives  were used to launch  a massive  50 kg iron ball. It created a huge depression where it had landed and now it has become a pond. The fire power was so incredible, the Gunner had to jump into a water tank close to the cannon to avoid shock waves upon firing.  Its  gunner, in the past, is said to have died on the spot upon firing the cannon.   It is said that ight people and one elephant were dead besides the collapse  of many houses in Jaipur in the wake of shake waves created by Jaivana.
4-wheeled carriage. Jaivana cannon, world's largest canon,Rajasthan Inner Voice
Jaivana cannon, world's largest canon,Rajasthan  Flickr
The Jaigarh Fort fort was built by Jai Singh II in 1726  mainly to protect the Amer Fort and its palace complex.  From here, one can have an amazing view of the Aravali range of hills and the Amber Fort. The media reports point out that the cannon foundry, museum and armory chamber need better maintenance and publicity to get more tourists to this beautiful place.