Monster or mirage?

Written by Alexander T. Lovcanski. Published for The Skeptic online on 30th August 2010.

The initial report and its subsequent versions

On 22 July 1933, a London businessman, George Spicer, with his wife, was driving on the road from Dores to Foyers along the southern shore of Loch Ness (Scotland) when their attention was drawn by an unidentified object which appeared on the road straight ahead. The time was between 1530 and 1600L. Spicer gave his initial account of the incident in a letter to the Inverness Courier (4 August 1933), as follows:

I saw the nearest approach to a dragon or pre-historic animal that I have ever seen in my life. It crossed my road about fifty yards [45 m] ahead and appeared to be carrying a small lamb or animal of some kind.

It seemed to have a long neck which moved up and down in the manner of a scenic railway, and the body was fairly big, with a high back; but if there were any feet they must have been of the web kind, and as for a tail I cannot say, as it moved so rapidly, and when we got to the spot it had probably disappeared into the loch. Length from six feet [1.8 m] to eight feet [2.4 m] and very ugly…

In consecutive retellings of their story, however, the Spicers claimed that what was earlier described as a smaller animal being carried by a monster, was probably ‘a long tail swung round to the far side of the body’, appearing as if it was ‘flopping up and down’ at a place where neck joined the body (Gould 1969:44). Other, more important, discrepancies concern the creature’s length, which was, on recollection, estimated to be at least 7.6 m, and its distance from the witnesses – about 180 m. In another version the monster grew even more, this time to about 10 m (Holiday 1969:31). Its height was guessed at 1.5 m (but see Figure 1).

Fig.1: The Spicers’ sketch of the object they thought they saw on the road (after Gould’s reconstruction) with a corrected object-to-road ratio. The original version is faulty because it is incompatible with the claim that ‘when on the road, it [the creature] took up practically the whole width of it’ (Gould 1969:44). Yet the drawing depicts the object spreading across not only the road, which was allegedly between 3 and 3.6 m wide, but also the grassy verge on either side. This makes the object-to-road ratio inaccurate and the original drawing misleading as the object had to be considerably smaller.

Nor is it clear how the incident ended. According to Gould, the creature was ‘in sight for a few seconds’ before it crossed the road and presumably entered the lake. More peculiar is the subsequent version published by Whyte (1961), where it is said that, by the time the Spicers had reached the spot where they thought the object had been on the road, ‘there was no sign of it’, as if it had suddenly vanished. Furthermore, there are conflicting reports about whether the witnesses had pulled over (Holiday 1969:31) or whether they had just slowed down as they approached the place in question (Gould 1969:46).

Despite these inconsistencies, this remains the first published report of a monster allegedly seen on land (instead of water) and the first one that mentioned a long neck. Prior to it, the eyewitness descriptions varied greatly. But after its publication a dinosaurian image was embedded into the public’s imagination, and many students of the mystery have accepted it as positive evidence of an unknown animal living in Loch Ness.


Unfortunately, the precise location of the encounter is not known. Despite the assistance of George Spicer and Alex Shaw, the latter was road constructor for the Dores area at the time, Gould was unable to determine the exact spot (Gould 1969:46f).

Spicer was sure that they had passed Dores and were on their way to Foyers along the B852. For the most part, this runs parallel to the southern shore of Loch Ness, but he could not remember whether or not they had passed Whitefield when they noticed the object (Ibid.:44). Holiday (1969:30) narrows the spot to just before Whitefield, some 6.43 km from Dores and 12.87 km before Foyers (Figure 2). For all practical purposes, we may regard this general area as the most probable place of the incident.

Fig.2: A plan of the area where the incident allegedly occurred. The Spicers were probably at A when they saw the object at B (some 100 m ahead).

More important are the physical features of the ground where the Spicers claimed they had their encounter. The road had a ‘slight rise’ and the unidentified object was positioned either on top or just behind this rise (Gould 1969:44-5). The Spicers’ account also suggests that there were no turns in the road and that it ran in a straight line prior to the incident. This means that their apparent horizon was between 50 and 200 m head-on, albeit slightly lifted because of the brow.

Unknown animal hypothesis

Many investigators regarded the Spicers’ report as evidence for the existence of some kind of animal unknown to science.

The proposed hypotheses included: an extinct plesiosaur (Northern Chronicle, 9 August 1933); a giant newt (Gould 1969:165); a gigantic version of a 0.35 m segmented invertebrate Tullimonstrum gregarium, known only from the fossil record (Holiday 1969); and a long necked pinniped (Coleman and Huyghe 2003:99-101).

But if the object was an unknown animal 1.5 m high and 7.6 m long (tail and a fully extended neck not included), then it would weigh in at a staggering 10 tonnes (the value derived from the scale model calculation of the volume, which would be 10 m3, and the assumption that its density would be similar to most of the known vertebrates at 1000 kg/m3). How could an aquatic animal the size of two fully grown Indian elephants be able to drag its bulk across roads alongside Loch Ness and remain undiscovered? Could such a beast disappear from view in a matter of seconds?

Evidently, the unknown animal hypothesis raises more questions than it answers, thus а rational explanation is needed.


Commenting on the Spicers’ experience, the Inverness Courier (4 August 1933) suggested that what they saw could have been a large otter carrying a young in its mouth. Sceptical authors accepted this explanation (see Burton 161:155; and Campbell 1986:112). Other explanations included a group of deer, feral goats or badgers (Raynor 2005, 2008, 2009), and a hoax (Campbell 2008).

As the creature was 1.8 to 2.4 metres long, it is reasonable to assume that it was in fact a common Eurasian otter (Lutra lutra). The average length of these animals is about 1.1 m, but they are known to reach greater size. According to Holiday (1969:50f), the largest otter recorded in Britain measured 1.67 m, yet Burton claimed that a 2.4 m specimen was caught on the Shetland Islands in the nineteenth century (Welfare 1980:118). The animal (Lontra canadensis) shot in Maine (USA) in 1949 exceeded 1.67 m and may have even been 1.95 m long when alive (Arment 2006).

Mirage hypothesis

The Spicers’ description of an otter suggests the presence of a specific phenomenon which must have grossly distorted the appearance of this animal. There are two principal clues to the identity of that phenomenon: weather conditions on the day of the sighting and the position of the object relative to the observers (the position was dependent on the features of the terrain).

Gould notes that the weather was ‘fine’ at the time of the incident but provides no further description (1969:43). Other sources give more details and state that ‘the sun was shining brightly’ (Cornell 1977:11) indicating that it was a ‘hot July afternoon’ (Shine 2006:7). According to the weather station at Inverness, 18 km north-east, at 0900UT (1000L), the temperature was 16º C but it rose to 18.6º C by 1700UT (1800L) with a total of 3.5 hours of sunshine during the recording period. Visibility was very good, varying from 20.1 to 50 km with medium amount of cloud (4/8). At 1700UT a light wind (force 1) was blowing from the south-west (240º) and the pressure was 1019.6 mb (data from the UK Meteorological Office). Evidently, the weather was very quiet and ‘uneventful’ that day, and the conditions may have been similar over a wider area, including Whitefield. In fact, the air temperature on Loch Ness may have been slightly higher due to the lake’s ability to retain a lot of heat (microclimatic effect). This assumption is strengthened by the fact that the sun was still very high in the sky (at 45º altitude) in the south-west direction (azimuth of 230º) at 1545L when the Spicers saw the object.

As the hot road is radiating heat (accumulated throughout the day) the air in the first few centimetres above the road becomes significantly warmer than the air above it. The colder layer is formed partly because of the temperature drop-with-height and partly due to the cooler air blown-over by a light SW wind from the surrounding hillside of Whitefield. These conditions would generally produce a large temperature-lapse, which could cause abnormal optical refraction. Optical refractive-index (n) is dependent on temperature but also on pressure; the higher the pressure, the higher the n (at the time, the pressure was almost 1020 mb). In fact, large n is necessary for an inferior mirage to occur.

Aside from meteorological factors, mirages also require specific terrain conditions – these were present at the time of the Spicers’ sighting.

The Spicers were driving an Austin (open) 12 hp, which means that their eye-level was at around 1.5 m above the road (an average Austin model from the 12/4 series had a seat-height at 0.86 m from the ground [Smith 2008]). The road ahead was gently upwards sloping before it gradually dipped. It was this rise that caused the apparent horizon to seem closer to the observers than it otherwise would; and it also could have made an otter appear taller. Because the source was near the horizontal plane of view of the observers, the optical path length through the intervening atmosphere was significant. As the distance was probably between 100 and 200 m, the object at the horizon was viewed from a low angle and this had a profound effect on the interpretation of the sight.

Although it is generally recognized that mirages could explain some lake monster sightings (see for example Gould 1969:108, 110-2; Lehn 1979; Shine and Martin 1988:164-7), only Maurice Burton and Adrian Shine have considered atmospheric refraction phenomena as a possible explanation for the Spicers’ report. Burton once suggested (Holiday 1969:50-1) that the object was an otter seen ‘under mirage conditions’ but he neither demonstrated this nor was he consistent because he also claimed that the sighting was caused by ‘a family of otters crossing the road’ (Burton 1961:155). Nor did Shine elaborate in detail his opinion that the ‘writhing shapes seen by the Spicers across hot tarmac’ were the result of a ‘heat haze’ (Shine 2006:13). In any case, ‘heat haze’ is not a mirage, although it too may have caused distortions of view (see below).

As indicated, the atmospheric conditions were such as to create a curved temperature profile that acted like a natural ‘lens’. Near the road surface ‘the [atmospheric] lens is very strong, so its focal length is small compared to the distance from observer to object’ (Young 2008), and it is here where the identical but inverted image of an otter below its geometrical position was created (the area where rays from the top and the bottom of the object intersect) (Figure 3). The otter’s lower parts (i.e. its legs) must have been out of sight because they were below the apparent horizon; thus only its body and tail remained visible. Consequently, the inverted image also contained only these features. The two images merged (at the ‘fold line’) into one and produced the appearance of a single, relatively tall, and roundish object with a substantial extension.

Fig.3: The geometry of an inferior mirage in the Spicers’ case. Light rays that are reflected from the caustic produce the inverted image (X′) of those parts that are above this discontinuity in the thermocline (X). The lower parts of an otter are below the apparent horizon, hidden by the dip (D) in the sloping road. Not to scale.

The imaging properties of a lens produce not only distortions but magnifications as well. Magnification in a vertical plane would have occurred at the ‘transition zone’ where the upright and inverted images joined. Because the Spicers were situated very low (relative to the object) their eye level was closer to the ‘lens’ at the horizon. Of course, the closer the lens, the more powerful it becomes and, thus, subtends a large angle at the eye. Consequently, the resultant image was vertically stretched at a place of mergence, making it look taller than the original source (see Figure 4). In fact, we may deduce that the image’s angular height (0.22º) was more than two times as much as that of the otter if viewed from the same distance (say 100 m) under normal atmospheric refraction. This means that the object looked at least 0.4 m tall for a given distance, and may have even appeared taller if the estimated distance was exaggerated. Its angular length would be over 1º, which may seem small but in reality objects near horizon appear much bigger due to the optical illusion effect (induced by a mirage and other factors) (see Figure 5).

Fig.4: Diagram showing how the upright (Y) and inverted (Y′) images merge to form a single ‘monster-like’ object. The line of mergence is actually a continuous transition zone where an appreciable vertical magnification occurs (because a single point on the object appears to fill the aperture of the atmospheric ‘lens’). An atmospheric disturbance caused by convection from the heated ground is being propagated by the southerly wind flow. It is this mechanism that produces undulating appearance of the tail and the pulsating movement of the body.

Fig.5: How the image would actually have appeared at a range of 100 m. Because the eyewitnesses were moving during the observation, their field of view (FoV) was slightly reduced from the average 180º x 150º (the so-called ‘tunnelling effect’), which made the object seem larger than if viewed from a stationary position.

As for the ‘undulating’ appearance of the ‘neck’ and the ‘jerky’ movement of the body, the ‘heat haze’ effect (more adequate term would be the ‘small-angle scattering’ or ‘angle-of-arrival-fluctuations’) seems to have been responsible. Actually, this is what astronomers call ‘scintillation’ where ‘a refractive-index undulation in the atmosphere acts as a lens, focusing the starlight’ and so magnifying the stars which seem to exhibit motion (Dravins et al. 1997:177). The undulations in the observed image were produced by the constant (but irregular) flux of warm and cold air, where the former rises and the latter descends, causing apparent frequency of the undulations. Any image viewed through this turbulence will appear to vibrate because of the angular deviations in the light path. The otter’s tail was positioned lower than the rest of the body where such turbulence would be at its strongest, and this is why it appeared to undulate, albeit not as much as it is shown in Gould’s exaggerated drawing. This mechanism could have caused brief magnification of the image as well.

Small-angle scattering might have also been responsible for the ‘motion’ of the object which seemed to move in ‘jerks’. The Spicers reported that the ‘monster’ was crossing the road from left to right (from SE to NW), heading towards the water (see Figure 2). But this would mean that the otter was going backwards. The confusion about the movement comes from misinterpretation of the tail as being a ‘neck’. In fact, the otter must have travelled from NW to SE, away from the lake, but due to the southerly wind, the unsteady air flows above the road were channelled to N, NW direction. Thus, a ‘trembling’ motion flowing from left to right was exhibited across the image, and this gave the illusion of physical movement.

The mirage hypothesis can also explain the subsequent sudden disappearance of the ‘monster’. If the distance to the object, when first seen, was some 100 m and the Spicers were driving at 32 km/h rate (Whyte 1961:77), then they would have reached the spot in 11.25 s. This is far too short a time for a 10 t animal to just ‘vanish’. Instead, the restricted geometry between the observers, mirage image and a source (otter), made the observed image to disappear abruptly by moving to higher (closer to the source) ground (exceeding the critical angle of view). By the time the Spicers have arrived to the place where they thought the animal had been it was gone. In vain they may have inspected the area on the right side of the road trying to find their ‘monster’. Had they bothered to look for it on the left side, perhaps, they would have sighted their quarry – an ordinary river otter.


Evidently the observers saw an inferior mirage of a large otter which momentarily crossed the road. Such a mirage completely explains the object’s appearance (its shape) and its size. The reported movements of the image are satisfactorily explained by a constant heat flux above the ground (producing small-angle scattering effect) and the prevailing flow of wind.

Mirages are not optical illusions but can elicit them so that the observer is mistaken about the true nature of the observed image and its source. This is especially true if the observers are in a state of expectancy as was probably the case with George Spicer and his wife. Obviously, they have been misled by a combination of ordinary meteorological and zoological stimuli.


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Acknowledgments: I acknowledge the assistance of Steuart Campbell, Hazel Clement, Richard H. Raynor, Frank Smith, Nick Sucik, Mirjana Trivich and Professor Andrew T. Young.