The River Jordan and Sweetpea are electric engines on the first railway on Mars.
River Jordan was the first one built, being the product of a collaboration between the nations who established the colony.
Sweetpea was donated by a coronal aerospace guild and assembled onsite. Her parts were imported and her blueprints were crownmade, so her visage is coronal.
Visage and the nature of living transport
Engines take the image of their creators. Their faces are not organic, and are more like a vessel for helpful senses and communication tools.
They come alive soon after they are built, once out of eyeshot for any moment. Attempts to stare at a new engine to see it stir are foiled somehow (blinks, saccades, CCTV malfunction, momentary lapse in attention). Not all engines come alive, as their animacy is often (but not always) decided by the intent of the builder.
Living engines can assess their circumstances and make judgements based on them. They are useful in volatile situations as an expert second opinion on conduct and design, and are capable of sensing external and internal problems quickly.
In calmer periods, they may not get adequate stimulation, and their personalities may interfere with their efficiency. For this reason, railways have their preferences when they build and purchase engines.
The facial material ends at the surface of the machine and is inscrutable in compositionโthe material appears to be made of itself, and is unusable for any other purpose besides as an engineโs interface with the world. If damaged, the material heals. If removed, it disappears. The conceptual self-referentiality of enginesโ faces, souls, and senses deter scrutiny.
Living machines exist as a fact of the universe. Their animacy is cloaked in an analysis-averting antimeme.
Engines designed and built by humans possess dual-pinhole pupils that dilate into an elliptical shape, granting them a broad field of view and tolerance of rapid changes in light levels (such as in going in and out of tunnels). Deep set zygomata allow them to look directly to their sides, and with the dual-pinhole setup, they maintain some depth perception in monocular sight. Their pupil shapes are hidden by their black irises, which absorb glare. They can see clearly to their front and sides, but canโt see up or down very well. A tapetum lucidum retroreflects incoming light back through their retinas, granting them vision in darkness. The nictitating membranes and long eyelashes protect the eyes from dust.
The chemicals engines are capable of detecting are relevant to their purpose, e.g. distinguishing coal, gasoline, diesel, and wood fires from their smoke but not being able to distinguish or detect food smells. Similar to how cats, obligate carnivores, have lost their ability to taste sugar due to its absence in their diet, but can taste ATP for its presence in meatโengines can parse environmental and industrial scents, but will have wildly varied responses to food and fragrant compounds, often being unable to notice them.
To investigate an aroma, they slightly lower their bottom lip to take air into their vomeronasal organ located behind the upper incisors.
Engines do not require oxygen, but if debris enters the nasal passage, human engines will sneeze to:
Ensure their voice resonates properly,
Keep their olfactory facilities clean, and
Indicate to engineers that particle buildup may have occurred in other places, such as the boiler tubes for steam engines.
Just as the tongue is the only colored object on a human engineโs face for distinguishability, so are the teeth on coronal engines. The positions of the upper and lower jaw indicate tone, functioning in communication similarly to eyebrows.
Coronal engine eyes consist of an armored cornea surrounded by a cuticle and muscular eyelid. The cornea moves with the help of the embedded eyestalk supporting it. The cuticle is lubricated with an oil-based film and is less susceptible to irritation than the aqueous solution on human engine eyes. The undersides of the eyelids and surface of the cornea are covered in setae, preventing chafing and reducing airflow on the cornea. The hairs catch debris and are combed out by the lids with a puckering motion.
To make up for unenhanced vision by human engine standards, coronal engine hearing is advanced, allowing the listener to pinpoint sound sources through triangulation of the four inner ears. Coronal engines, too, channel sound through their incisors and into their internal ears via the acoustic windows at the hinge of each jaw.
Coronal engines achieve their sense of industrial smell through the gustatory papillae that line their choana and pharynx. They supplement their olfaction by introducing cool air behind the heat pits inside their nares.
Coronal enginesโ thermoception is more efficient than living crowns, as coronal enginesโ faces do not produce heat nearly proportional to their mass.
Conversely, the tines heat up significantly hotter than the crown average for unambiguity in temperature tones. The origin of the tine thermal energy appears to be redirected from excess produced by the machinery, or from the faceโs temperature directly.
Engines are capable of listening from within their cabs with greater acuity than mere conduction of sound through the body would suggest. Other unsubstantiated sensory abilities include:
Discernment of water/fuel quality within the framework of taste though intake alone
Somatosensory awareness in the entire body, not just the face
