A Gate is a means used by the living to enter the Other Side. (It is a colloquial term used by Lockwood & co.) However, a protective gear must also be worn to survive and navigate the world of the dead.
Description of a Spirit Gate Edit
Basically, a gate has to have a large amount of Sources, especially strong ones, gathered inside some form of a barrier; and, some form of a guide (usually made of iron) must be positioned to intersect the barrier where both ends of the guide are located outside the barrier. The guide must not be touching the Sources and the death-glows below it when the Sources are piled. (Note: the barrier and guide are not official terms used in the books, the books use no term to collectively identify those functions.)
The multiple Sources grouped in a single spot create a wide opening as a gateway between the worlds of the living and the dead. The gateway would look like a column beaming up the from the Sources. The barrier prevents the spirits to cross to the living world but allows the living to access the gateway. The barrier itself must be strong enough to handle, and not be broken by, the gathered Sources' collective spiritual energy. The guide would have one of its ends superimposed in the Other Side when the gateway materializes. It serves to ward off ghosts, creating a pathway, and to lead a person in crossing the two worlds . Although a direct crossing of ghosts to this world is prevented, other ghosts, not inside the barrier, would be stirred and become active around and near the gate.
Chronologically, the confirmed access to the Other Side in the west was the Bone Glass of the 19th century, the Fittes's gate on the 20th century, and the Rotwell's gate on the 21st century. Donald and Celia Lockwood's travel to the east had explored that shamans or witch-doctors had been culturally travelling to the Other Side. However, the beginning of the shamans's practice was not identified.
Mentioned Gates Edit
The Shamans' Gate Edit
Specially made Spirit Houses were used as gateways by Polynesian shamans/witch-doctors from New Guinean hill country and West Sumatra forests. The materials used to make the Spirit Houses were not made clear, only that they were "specially" made, but still it stored a collection of Sources. The houses were accessed only in crisis for the reason that crossing to the other side stirs ghosts. Additionally, spirit houses were built away from villages and near streams to keep ghostly activities in the minimum and far from people. 
Rotwell's Gate Edit
The Rotwell Agency used an iron chain, as large as the chains used for docking ships, laid on the ground to enclose the Sources. The chains worked like a protective circle (the barrier) that, instead of protecting an agent inside from an outside spirit, keeps the ghosts within it. The gate, more like a dark swirling portal, is formed above the ground like a column. Additionally, another iron chain (the guide), a medium-weight one, was attached from a post, at some height (about Lucy's shoulder), outside the iron chain circle and goes through the gateway. One end of the smaller chain was superimposed to the Other Side. 
Fittes's Gate Edit
The Fittes Agency may have had different versions of its gateway though the long years that it had existed. The Gate that was found consisted of a pit where Sources were laid, an iron wall (of about Lucy's knee height) that circles the pit, and an iron walkway built along and connecting the two sides of life and death. The pit allowed for more Sources to be stacked and for a walkway, above the sources, to be made. The iron wall (the barrier) instead of a chain made the structure sturdier and permanent. The walkway (the guide) was simply an easier and durable path to use and see instead of an iron chain that the Rotwell Agency had used. 
Lockwood and Co.'s Gate Edit
Lucy Carlyle, Anthony Lockwood, George Cubbins, Holly Munro, and Quill Kipps modelled their spirit gate from the Rotwell's gate. They wound their agents' iron chains to create a thicker chain for the circle and the guide. Jessica Lockwood's bed and the artefacts collection of Donald and Celia Lockwood were used as Sources.
Gears and Equipment Edit
Chiefly, a protective gear must be worn to ward off spirits and to shield off the deadly cold atmosphere of the Other Side; and, some form of seeing device must be used by a person past his/her Talent age to see ghosts. Other equipment were used by the Fittes Agency and the Orpheus Society for their nefarious plans.
Below is a list of identified equipment: Edit
- Bone Masks - used to see spirits; taken from Polynesian Shamans.
- Spirit-capes - it protects the user from the Other Side's chill and minimally from the spirits; some made with feathers (worn once by Anthony Lockwood and worn twice by Lucy Carlyle), one made with feathers but coloured pink and orange (worn by Quill Kipps), one was made with pelts (worn by Holly Munro).
- Creeping Shadow armour - it protects the user from the Other Side's chill, seems to fully stave off spirits, and seems to have its own ghost-seeing device; it is made by Rotwell's Agency.
- Crystal Goggles - used to see spirits; made by Fittes's Agency and the Orpheus Society.
- Silver-capes and silver-gloves - it protects the user from the Other Side's chill and minimally from the spirits (worn by Marissa's men, Anthony Lockwood, and George Cubbins); made by the Fittes's Agency and the Orpheus Society.
- A full body suit - composed of a silver chainmail, iron stilts that cover the legs and feet, and a pair of metal gloves completely protects the user from spirits and the cold. . The set of equipment was worn by Fittes scientists and Orpheus Society Members.
- ↑ The Empty Grave, IV: The Siege of Portland Row, Ch. 18: " ...when Lockwood and Co decided to make a gate and discussed how to make it"
- ↑ The Empty Grave, V: Fittes Hous, Ch. 16
- ↑ The Creeping Shadow, V: The Iron Chain, Ch. 24: "...when Lucy and Lockwood entered a Rotwell Warehouse"
- ↑ The Empty Grave, IV: The Siege of Portland Row, Ch. 22: "...when Lockwood and Co. made their way to Fittes's House of Dark London"
- ↑ The Empty Grave, IV: The Siege of Portland Row, Ch. 18: " ...when Lockwood was allocating capes"
- ↑ The Empty Grave, III: A Body in the Street, Ch. 16: " "I knew the voice; and my guess was immediately confirmed, for at that moment Lockwood stabbed his flashlight on and shone it directly at the shape. The blaze revealed the secretary of the Orpheus Society , long white hair pluming out around a giant pair of goggles, a loose-fitting chain mail suit hanging over his dark coat. His feet and shins were encased in the top of a pair of pneumatic iron stilt-legs that adjusted, hissing, as he moved. His hands wore metal gauntlets, their fingers ending in foot-long stiletto claws. He cried out as the flashlight beam blinded him, raising one arm before his face.""