86 Meat refrigeration time. However, in many cases there is a need to measure temperatures over a long time period. In these situations a temperature recorder is required Historically, the temperature history of a point has been obtained usin temperature sensor connected to a moving chart. In its simplest form this is a stylus on the end of a bimetallic strip that bends in response to tem perature changes and scratches a continuous trace on a carbon chart moved by a clockwork motor. More sophisticated devices use electrical tempera ture sensors attached to a small chart recorder. The recorders can be driven from batteries or direct from the mains and the chart can be circular or rec angular and mounted on a drum or on continuous rolls. Typically instru ments will provide a continuous trace for up to a week, but some specially developed for long distance shipboard transportation of meat can operate for 6-8 weeks Increasingly, solid state electronic devices are being used to obtain the temperature history of a point. In most solid state devices the output from an integral electronic sensor is measured at set time intervals, converted to a temperature measurement and stored in a computer memory chip. In a small number of devices the interval between recordings can be adjusted and recordings started using buttons or switches on the instrument and the temperatures examined on an in-built display. a development is the use of small printers that can either be used to print out the temperatures as they are measured or attached after data collection is finished and the whole temperature history printed out. However, with the majority of instruments a small computer is required to set up start times, logging intervals and so on and recover the temperature recordin With many systems it is difficult to look at the temperature while it is being recorded or even check that the required information has been obtained before leaving the recording site. Some of the newest instruments are totally encapsulated in waterproof plastic and can be placed in direct contact with solid or even within liquid foods. Solid state devices can be very small, effectively tamper proof, and the value of the temperature at set times easily obtained, but the requirement for an associated processing facility substantially increases their cost. In many cases moving chart instruments may still provide the most economic and convenient solution to a monitoring problem. If precise temperature values at certain times are not required, then a quick examination of the chart may be sufficient to show that the temperature of the display cabinet, store room or transport vehicle has kept within the prescribed limits. However, obtaining tempera ure values from a small chart can be time consuming and inaccurate. In some situations the actual or relative position of the sensing points is important, whilst in others the position of maximum or minimum temper ature is required. There are few, if any, commercial sources of multi-point temperature probes and most have to be specially constructed. The sensors are attached to basic probes constructed from composite fibre or wood oftime. However, in many cases there is a need to measure temperatures over a long time period. In these situations a temperature recorder is required. Historically, the temperature history of a point has been obtained using a temperature sensor connected to a moving chart. In its simplest form this is a stylus on the end of a bimetallic strip that bends in response to tem￾perature changes and scratches a continuous trace on a carbon chart moved by a clockwork motor. More sophisticated devices use electrical tempera￾ture sensors attached to a small chart recorder. The recorders can be driven from batteries or direct from the mains and the chart can be circular or rec￾tangular and mounted on a drum or on continuous rolls. Typically instru￾ments will provide a continuous trace for up to a week, but some specially developed for long distance shipboard transportation of meat can operate for 6–8 weeks. Increasingly, solid state electronic devices are being used to obtain the temperature history of a point. In most solid state devices the output from an integral electronic sensor is measured at set time intervals, converted to a temperature measurement and stored in a computer memory chip. In a small number of devices the interval between recordings can be adjusted and recordings started using buttons or switches on the instrument and the temperatures examined on an in-built display. A development is the use of small printers that can either be used to print out the temperatures as they are measured or attached after data collection is finished and the whole temperature history printed out. However, with the majority of instruments a small computer is required to set up start times, logging intervals and so on and recover the temperature recordings. With many systems it is difficult to look at the temperature while it is being recorded or even check that the required information has been obtained before leaving the recording site. Some of the newest instruments are totally encapsulated in waterproof plastic and can be placed in direct contact with solid or even within liquid foods. Solid state devices can be very small, effectively tamper proof, and the value of the temperature at set times easily obtained, but the requirement for an associated processing facility substantially increases their cost. In many cases moving chart instruments may still provide the most economic and convenient solution to a monitoring problem. If precise temperature values at certain times are not required, then a quick examination of the chart may be sufficient to show that the temperature of the display cabinet, store room or transport vehicle has kept within the prescribed limits. However, obtaining tempera￾ture values from a small chart can be time consuming and inaccurate. In some situations the actual or relative position of the sensing points is important, whilst in others the position of maximum or minimum temper￾ature is required. There are few, if any, commercial sources of multi-point temperature probes and most have to be specially constructed. The sensors are attached to basic probes constructed from composite fibre or wood of 286 Meat refrigeration