Apparatus Technology, also known as cage-connecting*, was a Holderhold technology based on the well-known magical phenomenon of gem connecting.

Cages

Connecting gems was a relatively simple step for even weak spellcasters. Gem cages were the difference between plain gem connections and apparatuses: by setting up a frame around a gem, usually out of metal, the connection's properties could be greatly strengthened or even modified.

The science of caging could be greatly refined. While primitive cages simply strengthened the connection, usually simply augmenting its capacity (allowing more energy to be transferred, or allowing smaller gems to be used), with more intricate cages, other properties could be achieved, such as having more fine-grained control over the connection (useful for communicators), being able to establish networks of more than two connected gems and even choosing which connection to activate at a given time, setting up a broadcast source that other gems could simply be tuned into without modifying the emittor, or even change the exact type of energy being transmitted. Caging could not particularly improve the possibility of transporting matter through connections, however.

Technologies

These are the known technological applications of caging.

Heat Transfer. By far the most common use was the direct transfer of heat energy; Holderhold positioned captor gems in Dragonloss as early as 70 OW. These energy capting apparatuses were typically used as broadcast emittors, into which receiver gems could be tuned without accessing the positioned emittor. The typical application was to power ship boilers, without the need for fuel.

Kinetic Transfer. It was possible to run a motor somewhere, generating torque, and transfer that energy through apparatuses - usually by rotating the emittor gem directly, and linking the receiver to rotate in the same manner. Later, very intricate apparatuses could control how much of the torque energy to receive, but often this was just controlled at the emitting motor. Small ships could be powered in this way, driving the screws directly without need for a boiler.

*Communication. Apparatuses could of course be used for communications with all kinds of signals, as was the primary application of connections anyway. Apparatus communicators rapidly became very fancy, utilizing frequency modulation to achieve a very high bandwidth. Initial progress was still using light-based codes, but enabling mutliple communicators to tune in to the same frequency; by 73 OW, first voice transmitters were built. This opened the door to any and all kinds of transmitters. It took a while for industrial production to be cheap enough, and the network controls simple enough, to establish a statewide communication network; this was only done in the 120s and 130s, and utilizing large copper-antenna receivers and simple apparatuses which were very large but easier to produce.

Limitations

Cost. Building advanced apparatuses had a lot of potential, but the construction of the precise cages, and controls to manipulate them around it, required a lot of careful effort - up to several tendays of work for skilled laborers - and some precise spellcaster input as well. Simple apparatuses could be produced relatively cheaply on an industrial scale, though.

Capacity. The Weave always had a limited capacity for connection use (energy extraction was wholly infeasible on an industrial scale, and connecting to fugues was surprisingly difficult). More advanced cages could achieve higher bandwidth before straining the Weave, so things like communication were never an issue, but transmitting energy for heavy use - especially on the absorbing end - was always limited.

Distance. Through the air, ruby connections were generally never a problem. This did require a not negligible initial energy investment, however, which slightly complicated widespread communicator networks. Apparatuses could operate across the entire width of Oshmondu and lose only 30% of output. Underground was a different matter, however; though stone was not an issue, interference from metal and gem deposits, and natural or artificial magical sources, greatly hampered connections. Even for advanced train energy networks in the 150s, it was impossible to achieve anything more than a 2% energy yield over a distance greater than 50 kilometers through average Caverealm volume.

Fragility. Apparatus cages were finnicky, especially the more advanced and precise ones. They had to be carefully stored and used, because of the likelihood they might break.

Undesired Use. Due to the fact that drawing energy is much easier than ingesting it, there was always the danger that third parties might link into an apparatus connection, especially for energy broadcast networks where one simply needed to find out the cage tuning. It was impossible to turn off a connection for specific users; in such cases, one had to expensively retune the emitters and all the receivers. In early Dragonloss systems, there was in fact no other choice than to give up or destroy the receiver gem, because it could not be extracted back out of the volcano.